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TONGO MINE

MINING OPTIONS DESKTOP STUDY

FOR

December 2014

Confidentiality Notice This document is strictly confidential and is the property of

Paradigm Project Management (Pty) Ltd. No part of this document may be reproduced, translated, stored in a retrieval system or transmitted in any form to any third party by any means, without prior written permission of Paradigm Project Management

(Pty) Ltd.

TONGO MINING OPTIONS DESKTOP STUDY

Title: Tongo Mining Options Desktop Study

Paradigm Project Management (Pty) Ltd

Number: P1529 Date: 2014/12/01 Revision: 2 Confidential Page 2 of 87

EXECUTIVE SUMMARY

Paradigm Project Management (Pty) Ltd (PPM) has completed a Conceptual Economic Scoping Study (CESS) for Stellar Diamonds Plc (Stellar) for the Tongo Mine in Sierra Leone. The CESS indicated a viable project that could proceed into the next phase of development. However, the underground shrinkage mining method proposed in the CESS, whilst producing positive NPV and IRR metrics, does not support early cash flow generation. Stellar believes that there may be surface mining options that could realise early financial returns when operated in parallel to the development of access to the underground mine. This led to PPM being appointed to undertake a desktop study to consider various options for surface mining. Following its appointment, PPM conducted a brainstorming session. The purpose of the session was to identify and evaluate, at high level, the merits of various mining and hoisting methods. The surface mining options included: • Mechanised open pit mining options • Slot mining options – these include manual mining, Bauer trench cutting, raise boring, and

long hole drilling options The desk top study identified 13 possible mining methods. These were subjected to a qualitative assessment, to determine their relative technical feasibility and economic viability. The evaluation criteria that were used in the qualitative assessment included: • Suitability for kimberlite dyke mining • Practicality in the context of mining in Sierra Leone • Mining Track record • Capex and Opex burden • Support infrastructure requirements • Applicability to both surface and underground mining • Production Potential (Tonne/day) • Early production potential

The outcome of this qualitative assessment indicated that the most technically feasible and economically viable mining methods were: • Trench or slot - Underhand stoping • Trench or slot - Bench stoping

The suitability of these two manual mining methods was borne out by the indicative financial modelling that was conducted.





Indicative financial modelling was done on the following five selected mining methods, informed inter alia by the outcome of the qualitative assessment.

Mining method modelled Comment 1 Trench or slot underhand stoping Named underhand stoping in financial model 2 Trench or slot manual drill and blast Named Bench stoping in financial model 3 Trench or slot drill and blast from surface Named Long hole drilling stoping in financial model 4 Trench or slot Bauer trench cutter

Included because initial work was done at Koidu using this technology. Revisited taking on board the learning from this earlier work

5 Valley open pit mechanised mining

A hybrid of shallow open pit and shallow trench mining excavated from the open pit floor – initial calculations suggested this to be a viable method

The outcome of the financial modelling indicated that the most attractive surface mining option would be: Slot mining utilising the bench stoping mining method It is recommended that Stellar consider undertaking additional work to confirm the viability of this mining method. It is further recommended that the valley open pit mechanised mining method, being a hybrid comprising shallow trench mining and shallow slot mining be explored during a next study phase. The hybrid open pit mine would also provide a useful benchmark against which to measure the attractiveness of the slot mining option.





CONTENTS

1. INTRODUCTION 5 Background 5 The Brief 5 Structure of the study 5

2. BRAINSTORMING SESSION 6

3. QUALITATIVE ASSESSMENT 8

4. SLOT MINING – BENCH STOPING METHOD 14 Mine Scheduling and Planning 14 Mining Cycle 16 Hoisting 17 Mine Dewatering 18 Services 18 Ventilation 19

5. INDICATIVE FINANCIAL MODELLING 21

6. CONCLUSIONS 25

7. RECOMMENDATION 27

8. ANNEXURES 28 Discussion on mining method 12 28 Communication with Bauer: the Trench Cutting Investigation 29 Communication with Koidu 31 Trip report to Mauritius to view the Bauer technology 32 Note for the record – brainstorming session 37 Updated Tongo Resource 49 Financial model (Base Case) 54 Financial model Option A 81 Financial model Option B 87





1. INTRODUCTION

Background Paradigm Project Management (Pty) Ltd (PPM) completed a Conceptual Economic Scoping Study (CESS) for Stellar Diamonds Plc (Stellar) for the Tongo Mine in Sierra Leone during June 2013. The CESS indicated a viable project that could proceed into the next phase of development. However, the underground shrinkage mining method proposed in the CESS, whilst producing positive NPV and IRR metrics, does not support early cash flow generation. Stellar believes that there may be surface mining options that could realise early financial returns when operated in parallel to the development of access to the underground mine. This led to PPM being appointed to undertake a desktop study to consider various options for surface mining.

The Brief The strategic driver as defined by Stellar is to generate positive cash flow as soon as possible. PPM has been requested to consider other potential mining options, specifically open pit options which could decrease the lead time to full production levels and allow for continued production whilst access to underground workings is completed.

Structure of the study The following overall structure was adopted for this desktop study. It reflects a logical progression towards the recommended way forward. • Brainstorming session to identify mining and material handling methods • Qualitative assessment of mining methods • Indicative financial modelling of preferred mining methods • Conclusions • Recommendations





2. BRAINSTORMING SESSION A brainstorming session was conducted on Monday 09 June 2014. The purpose of the session was to identify and evaluate, at high level, the merits of various mining and hoisting methods. The outcome of this brainstorming session is documented in a note for the record (NFTR) which is appended to this report. The NFTR was submitted to Stellar on 22 June 2014. The NFTR was structured to address the following aspects of surface mining: • Mining concepts – open pit or slot mining? • Mining method – manual or mechanised? • Hoisting and material handling methods • Support requirements

The outcome of this brainstorming session resulted in twelve possible mining methods to be subjected to a qualitative assessment. One additional method was included following a discussion with Maxem and Sandvik as relates to the opportunity for surface drilling combined with underground ore extraction.

X section Mining method Material Handling Options 1 Valley open pit

Mechanised Mining Trucks and shovel

1a Valley open pit

Mechanised Mining - shallow open pit with shallow trench

Trucks and shovel, excavator

2 Vertical wall open pit

Manual drill and blast Manual lifting, scraper winch, Blondin

3 Trench or slot Under hand stoping Scraper winch, Blondin, Headgear and Kibble

4 Trench or slot

Manual drill and blast – bench stoping

Scraper winch, Blondin, Headgear and Kibble

5 Trench or slot

Drill and blast from surface – long hole drilling stoping

Scraper winch, Blondin, Headgear and Kibble

6 Trench or slot

Bauer Trench Cutter Mechanical - cutter

7 Trench or slot Bauer Grab Mechanical – grab 8 Trench or slot Large diameter holes from

surface Mechanical – drilling

9 Trench or slot Raisebore Mechanical – raise bore machine 10 Trench or slot Barge and cutter Mechanical - cutter 11 Trench or slot Road cutter Mechanical - cutter 12 Trench or slot Shallow vertical shafts with

reef drive Headgear and Kibble

Table 2-1: Possible Mining Methods





The mining methods that were assessed are briefly described: A Mining Method Description 1 Valley open pit Mechanised

Mining Typical open cast mine. Shovels and trucks, with benching and vehicular ramps (60deg slopes). The width of the pit at base to accommodate truck access. Depth of pit to full depth as required by the mine planning

1a Valley open pit Mechanised Mining - hybrid

As for 1, except pit is shallow and the fissure is mined utilising slot mining from the base of the shallow pit

2 Vertical wall open pit - Manual drill and blast

Steep sided pit with extensive rock anchors. Hand drilled blasted and lashed. There is precedent for this in Sierra Leone

3 Trench or slot - Underhand stoping

Similar mining method as to what is proposed for the U/G mine. Drill and blast on the incline. Blasted rock is scraped to the base of the excavation and hoisted vertically to surface using one of the suggested hoisting methods (preferred is the headgear and kibble on tracks on the foot wall)

4 Trench or slot - Manual drill and blast - bench stoping

Benches are created in the slot from which the drilling and blasting is done on a vertical face. Multiple benches and faces possible. Blasted rock is scraped to the lowest wide bench from where it is hoisted to surface

5 Trench or slot - Drill and blast from surface - long hole drilling stoping

Long hole drill is done in the slot from surface and rock blasted into the slot. Cleaning is done on the slot floor. Material is hoisted to surface

6 Trench or slot - Bauer Trench Cutter

Bauer Trench Cutter cuts 800mm wide contiguous slots from surface. Inclination of 80deg can be accommodated. Chips from the cutting process are pumped to surface and sent to a dewatering and screening plant

7 Trench or slot - Bauer Grab As for 6, except the slot is “pre-conditioned” – blasted and the material loaded using an hydraulic grab. The cross section of the grab similar to the cutter, resulting also in a contiguous slot

8 Trench or slot - Large diameter holes from surface

Proposal received from DeWet Drilling. Large diameter holes are drilled from surface (1.2m possible) at suitable intervals. The dyke material between the holes drilled using long hole drilling and blasted

9 Trench or slot - Raisebore Decline is constructed with an off reef drive, cross cuts and a reef drive. A raise bore machine is used to cut to surface and the chippings removed via the decline. Pilot hole drilled from surface before raise boring can occur

10 Trench or slot - Barge and cutter

Submersed dyke using “bund walls” to create a dam to float a cutter unit

11 Trench or slot - Road cutter Continuous miner approach – limited reach 12 Trench or slot - Surface

drilling with U/G extraction Shallow vertical shafts or pits (25m deep) constructed at about 150m intervals. Vertical shafts constructed using thermal spalling and drill and blast (refer method described in the annexure). Reef drive constructed between shafts. Long hole drilling from surface, blasting and cleaning from U/G. Material hoisted via the vertical shaft pits

Table 2-2: Mining Methods described





3. QUALITATIVE ASSESSMENT

A qualitative evaluation was applied to the mining methods selected for assessment. The evaluation criteria adopted are listed:

Criteria Considerations

Suitability for kimberlite dyke mining Dilution, poor definition, mine planning requirement

Practicality in the context of mining in Sierra Leone

Access to site, logistics, manpower, expertise requirement

Track record Previous history in mining operations Capex and Opex Impact on viability Support infrastructure Equipment, power, diesel Applicability to both surface and underground mining

Can the technology, method be relocated from surface to underground

Production Potential (Tonne/day) Production as a function of profitable production and sustainability while waiting for the U/G mine to be established

Early production potential The primary reason for surface mining Table 3-1: Evaluation Criteria

Ranking and weighting was applied to both the mining methods and evaluation criteria used. Weighting – this was applied to the evaluation criteria (number 1-5). A high number indicates a dominant impact of the criteria on the mining method under review Ranking – this was applied to the mining methods (number 1-5). A high number reflects the “attractiveness” of the mining method for the criteria under review For each mining method and criteria, a product of the weighting and ranking was returned in the following table. These products were summed for each mining method. Therefore the mining method with the highest “sum of product” number was adjudged the most attractive option. The following table reflects the outcome of this process.





The highlighted mining methods have been taken up in the financial model.

Mining Method

Suita

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for k

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dyke

mini

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minin

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ierra

Leon

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ecord

– pre

vious

his

tory i

n mini

ng op

eratio

nsCa

pex a

nd O

pex

cons

iderat

ions

Supp

ort in

frastr

uctur

e

Appli

cabil

ity to

both

surfa

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and u

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round

mini

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ducti

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tentia

l (T

onne

/day)

Early

prod

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"Sum

of P

rodu

cts"

Weighting 5 5 4 5 4 1 3 5

1 Valley open pit Mechanised Mining 0 2 3 1 2 0 2 2 511a Valley open pit Mechanised Mining 2 2 3 3 2 0 3 2 742 Vertical wall open pit Manual drill and blast 1 4 2 3 4 0 1 1 723 Trench or slot Underhand stoping 4 5 4 4 4 5 4 5 1394 Trench or slot Manual drill and blast - bench stoping 5 5 3 4 4 4 5 5 1425 Trench or slot Drill and blast from surface - long hole drilling stoping 3 3 2 3 3 0 3 4 946 Trench or slot Bauer Cutter 1 2 0 2 2 0 1 2 467 Trench or slot Bauer Grab 2 2 0 2 2 0 2 2 548 Trench or slot Large diameter holes from surface 1 2 2 3 3 0 2 3 719 Trench or slot Raisebore 1 1 2 2 2 2 2 0 4410 Trench or slot Barge and cutter 1 1 0 1 1 0 1 1 2711 Trench or slot Road cutter 1 1 2 2 2 3 1 3 5712 Trench or slot Surface drilling with U/G extraction 2 2 2 2 3 2 2 2 68

Ranking

Mining Cross Section





Notwithstanding the results of the assessment, the following mining methods were disqualified as having little or no potential.

Mining method disqualified Reasons

Valley open pit – Mechanised Mining Large strip ratio Vertical wall open pit – Manual drill and blast

With trench mining considered feasible, there would be no reason to hand blast and lash large amounts of country rock to create an open pit (albeit steep sided)

Trench or slot - Raisebore No early ore to plant possible – a decline is required to get underground to allow the setup of the raise boring equipment

Trench or slot - Barge and cutter No early ore to plant possible – extensive set up and time required to submerse the workings and start production

Trench or slot - Road cutter Very costly equipment and very limited reach / depth possible

Table 3-2: Mining Methods Disqualified

Following the qualitative assessment the following mining methods were taken forward into the indicative financial modelling work.

Mining method modelled Comment 1 Trench or slot underhand stoping Named underhand stoping in financial model 2 Trench or slot manual drill and

blast Named bench stoping in financial model

3 Trench or slot drill and blast from surface

Named Long hole drilling stoping in financial model 4 Trench or slot Bauer trench cutter

Included because initial work was done at Koidu using this technology. Revisited taking on board the learning from this earlier work


A hybrid of shallow open pit and shallow trench mining excavated from the open pit floor – initial calculations suggested this to be a viable method

Table 3-3: Mining Methods taken forward





The sketches representing these selected methods are reproduced:

Valley open pit Mechanised Mining – hybrid

S c rap e r

Win c h

Trench or slot - Underhand stoping

Trench or slot – Manual drill and blast – bench stoping





Trench or slot - Drill and blast from surface – long hole stoping

Trench or slot - Bauer Trench Cutter In order to ensure that there is alignment on terminology, the following definitions are used in the report and the financial modelling: • Pit: A mining module on strike • Stope: Entire side of the Pit being advanced (each pit has two stopes) • Face: Working area – part of a Stope where drilling is done • Panel: Another name used interchangeably for Face

For the underhand stoping and long hole drilling methods, the face is the stope.





The assumptions made regarding the practical depth of mining for each selected method are tabulated:

Mining method Depth

(m) Constraint

Trench or slot underhand stoping 30 Restricted by safe operation Trench or slot manual drill and blast 40 Benching is safer method Trench or slot drill and blast from surface 30 Restricted by drilling control Trench or slot Bauer trench cutter 25 Severely restricted by cutter control Valley open pit mechanised mining 25 + 5 Constrained by economics

Table 3-4: Assumptions regarding depth These depths have been adopted in the financial model calculations. It should be possible with adequate support and ventilation to extend the bench stoping method deeper should this be required. This should be explored in the next phase of the project.





4. SLOT MINING – BENCH STOPING METHOD Slot mining with bench stoping has been selected for further development as, at face value, it provides the most attractive mining method. Therefore, the associated services have been detailed for this particular mining method. It is accepted that these services will be applicable to all manual slot mining methods as outlined in this report. This work on services therefore enhances the pricing as reflected in the financial model.

Mine Scheduling and Planning It is currently proposed that the mine will consist of 3-4 mining pits each covering a strike length of 500m. Each pit will start mining at the centre of the 500m strike and as the benches develop to either side of the pit, it will be deepened by 2.5m and the next bench elevation will be created. It is proposed that 6 benches will be advanced simultaneously in opposite directions. This provides 12 working faces at any point in time. This will mean that a single pit can have 32 faces during steady state of which 6 will be mined simultaneously. This method provides good flexibility within each pit.

4.1.1. Face Naming Convention For the ease of scheduling each face will have a certain identification number. Example: Face 2East7 The identification proposed: • 2 refers to Pit 2 • East refers to mining advancing in an easterly direction • 7 refers to bench 7

This will assist with mine scheduling and planning.





4.1.2. Face Dimensions

The bench mining concept accommodates a working platform for the mining crews to drill from. The current proposal is for a 5m horizontal section sloped slightly upwards towards the face to allow for water to drain under gravity to the lowest established point in the pit for pumping to surface. The mining width is 1.5m and the face height is 2.5m. The expected advance per blast is 1.5m drilling 2m-long holes.





4.1.3. Mining Design Parameters (Single Pit Production)

Mining Unit Value Strike Length m 2 000 Dyke Width m 0.45 Mining depth m 40 Total fissure volume in situ m³ 36 000 Ore Density t/m³ 2.79 Total fissure tonnes in situ t 100 440 Dyke Grade cpht 120 Total carats in situ cts 120 528 Stope width m 1.50 Waste Density t/m³ 2.70 Total waste in situ t 226 800 Total ore mined t 327 240 Monthly horizontal face advance m 12 Ideal stope face angle ° to horizontal 90 Average Stope Length m 40 Mining Recovery % 98% Fissure tonnes per stope per month t 591 Tons waste per stope per month t 1 361 Mining Efficiency % 95% Fissure tonnes per stope per month t 561 Total tonnes per stope per month t 1 854 Total tonnes per stope per annum t 22 246 Number of stopes per pit No 2 Fissure tonnes per pit per annum t 13 465 Total tonnes per pit per annum t 44 492

Table 4-1: Mining Design Parameters (Single Pit Production)

Mining Cycle The mining cycle consist of three shifts per day namely: • Morning Shift – Drill & Blast • Afternoon Shift – Cleaning and Hoisting • Night Shift – Underground support and services

4.2.1. Drilling and Blasting

Drilling will start on day shift and 6 faces will be drilled simultaneously with hand held rock drills, air legs and compressed air. One drilling machine will be used to drill the 1.5m×2.5m face. Once the drilling is complete the miner will prep and charge-up the faces. All people will then move to surface and the blast activated towards the end of the shift. The re-entry period would be 30 minutes.





4.2.2. Cleaning The afternoon shift will clean the blasted ore from the benches. They will start at the top bench manually moving the material to the bench below. The two top benches will be cleaned manually and the 3rd bench will be equipped with a mechanical scraper winch. This winch will scrape the material towards the hoisting system. The ore will then be loaded from the 3rd bench into the kibble and hoisted to surface, where it is tipped into the headgear chute and into the dump truck.

4.2.3. Support and extending mining services Night shift will be responsible for supporting the blasted area and also to make the area safe of any loose rock. They will extend any service water and compressed air piping and ventilation brattices to prepare for morning shift and the drilling operation.

Hoisting

Hoisting of ore will take place just below the third bench of that section of benches being mined. The headgear will be a steel structure that will straddle the excavation opening and will run on rails along the length of the dyke. The rail gauge is estimated to be between 2.3m to 3m. The headgear structure will be equipped with a winch and a discharge chute. The winch will hoist the 1 or 2 tonne kibbles. The kibble will discharge ore into the chute, which will transfer the ore into a dump truck parked below the chute. Rails will be installed at 50m intervals on the footwall to support and guide the kibble running on wheels.





Mine Dewatering Submersible pumps will be installed at the lowest point of the pit, most likely positioned in the centre of the pit. Water will be discharged into a horizontal settler for water treatment. The suspended solids will be loaded out with a front end loader and transported to the plant for processing. The clean water overflow pumped to the service water tank for re-introduction into the service water system. Excess water will be pumped to an environmental dam for further treatment and discharge back into the environment if the water balance is positive. It is assumed that the mine will produce water at 100% of the consumption and therefore the pumping system will be designed to dewater at double the rate of the service water required for drilling.

Services

Services such as service water and compressed air will be supplied by a main line running along the length of the strike. Take-offs from the centre of each pit will extend down the pit and towards the faces for service water and compressed air supply. It is assumed that water consumption for drilling is 1m³ water/tonne of rock mined. It is assumed that each pit will have a dedicated mobile compressor, which will supply compressed air at 5 - 7 bar. The proposed mining plan suggests that 6 rock drills will be used during drilling and each will use approximately 130cfm. This means that a small 800cfm compressor unit will suffice.





Ventilation

Each pit will have its own ventilation system. An upcast ventilation column will be installed at the centre of each pit, equipped with 2 fans (one running and one standby). Ventilation brattices and curtains will allow the air to be sucked from the outer extremities of the pit into the top benches and allow it to flow down each face to the lowest bench and towards the centre of the pit where it will upcast through the ventilation column to surface. The challenge will be to have sufficient ventilation during the cleaning shift when hoisting takes place. It is proposed that a cover will be opened directly above the bench used for loading. These covers will be closed once the specific set of benches has been cleaned.









5. INDICATIVE FINANCIAL MODELLING The financial modelling for this Desk Top Study (DTS) was based on the results of the Tongo Mine Conceptual Economic Scoping Study (CESS) completed by PPM on 18 June 2013. The “Stellar Acquisition” option in the CESS has been used as the base case for this DTS. In addition, the revised Resource statement of 14 November 2014, as provided in Table 5-1, has been included in this DTS (Annexure 8.6). The Lower Grade model of 120cpht with a value of US$270/ct has been adopted for this DTS.

Tongo Dyke-1 Resource Dec-12

Resource Nov-14

Lower grade model

Resource Nov-14

Higher grade model

Tonnes 895 000 895,000 895 000 Grade (cpht) +1.0mm cut-off 120 120 165 Carats in resource 1 074 000 1 074 000 1 447 000 Diamond Value (US$/ct) 248 270 145 $ per tonne in-situ at average value 297 324 239 Contained Value US$ million 266 290 214

Table 5-1: Revised Resource This DTS has assumed that the shaft access and underground mining from this option will be retained. However, the access decline proposed in the CESS has been removed from the model and replaced by one of the five selected surface mining options. Whilst this may not be entirely accurate since, for example, the issue of a second access once the mine has gone underground would need to be addressed in any future feasibility study, it does provide a basis for comparison of the various surface mining options. In addition, the operating costs for the plant, engineering, manpower, and logistics have been amended to cater for the earlier production arising from the surface mining. It was necessary to make some assumptions as to the level of the support functions such as power generation, accommodation and messing, and logistics required for the early start of surface mining operations and these have been incorporated into the financial model. The following parameters were therefore retained as per the CESS: • Shaft waste • The schedule to complete the shaft • Underground ore mined via the shaft • Mined grade • Diamond value • Capital expenditure for all sections except the development of the decline • Working costs for all sections except the decline operations





The financial model for each of the five surface mining options has their capital expenditure and working costs added to the base costs for underground mining provided for in the CESS. This is to determine the effect on the Notional Profit and hence the cash flows. In order to ensure the compatibility of the comparisons, the same exchange rate that was used in the CESS (ZAR10.25 : US$1) has been retained. Three financial models have been prepared: • The base case – reflecting the financial modelling for the 5 selected mining methods • Bench stoping Option A – the bench stoping method included in the base case but

with the surface mining commencing 3 years earlier than assumed in the base case • Bench stoping Option B – the bench stoping method included in the base case but

with the surface mining commencing 2 years earlier than assumed in the base case Table 5-2 is the input sheet associated with the financial model, and reflects the most pertinent assumptions made.

Table 5-2: Input assumptions to the financial model

The summarised results from this model are indicated in Table 5-3. The comparison indicates the preferred option is for Slot 2 Bench Mining. The financial model assumes that the surface mining and underground development will commence simultaneously in Year 1. However two other alternatives have also been modelled whereby the surface mining commences either 2 or 3 years prior to the

ITEM UNIT VALUECOMMERCIALRevenue per carat $/ct 270Exchange Rate ZAR/US$ 10.25Diesel Price US$/l 1.31Diesel Price: Duty Exemption US$/l 0.93Capex contingency % 15%Opex contingency % 15%MANPOWERBurden % 10%TECHNICALIn-situ kimberlite grade ct/100t 120Recovery Efficiency % 100%Manned Hours per day Hours 16Manned Hours per month Hours 320Manned Hours per year Hours 3 840





commencement of development for the underground mine. These options are indicated in Table 5-4. Whilst it is not shown in this report in detail, reductions in the estimates used for the percentage of up-front capital required for the surface mining options, prior to commencement of the underground development, do not make significant changes to these results.





Table 5-3: Summary of financial modelling results

Table 5-4: Alternative modelling options

YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$

DTS 1 - Underhand Stoping 30 108$ 37% (12 537) 570 3 446 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788DTS 2 - Bench Stoping 33 340$ 43% (12 134) 1 109 6 668 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788DTS 3 - Longhole Drilling Stoping 29 130$ 35% (12 765) 334 2 680 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788DTS 4 - Trench Cutter 15 540$ 19% (16 442) (8 953) (4 132) (615) 7 645 11 792 14 158 15 364 14 171 10 260 7 215 7 136 2 788DTS 5 - Open Pit and Trench 24 680$ 28% (16 140) (1 728) 1 483 5 139 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788DTS 6 - CESS 23 438$ 27% (13 703) (3 558) 11 3 812 5 492 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788

NOTIONAL PROFIT NPV @ 10% IRR

YEAR -3 YEAR -2 YEAR -1 YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$

DTS 2 - Bench Stoping - Option A 20 628$ 28% (7 447) 3 067 2 597 (5 390) (3 537) (169) 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788DTS 2 - Bench Stoping - Option B 24 165$ 32% - (7 447) 3 067 (1 106) (3 569) (169) 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788

NOTIONAL PROFIT NPV @ 10% IRR





6. CONCLUSIONS

It was concluded that surface mining to supplement the underground mine is both technically feasible and economically viable. However, economic viability is ultimately determined by Stellar setting thresholds, as to what NPV and IRR are required. The financial model indicates that the most economically viable surface mining options are the three manual slot mining techniques. The following table provides the more qualitative comparisons of the five options considered in the financial model. Mining method

modelled Technical Feasibility Economic Viability

1 Trench or slot – underhand stoping

This is a similar mining method to that proposed for the underground mine. As the trench or slot mine is down to 25m depth, there is a safety concern for both the drilling and cleaning cycles.

This method is economically viable though it lacks the scalability and flexibility that the bench stoping method offers.

2 Trench or slot manual drill and blast – bench stoping

This is the most attractive slot mining method. It offers scalability and flexibility in that a large number of faces are available for mining. The number of mining benches and pits can be easily increased to increase production. This method provides the greatest degree of dilution control as the contact zone is evident in the vertical mining face.

This method appears to be the most profitable of the three manual slot mining methods.

3 Trench or slot drill and blast from surface – long hole drilling stoping

This mining method lacks flexibility and scalability as it is assumed that a single drill rig will provide for the long hole drilling from surface. But it is likely that the drill rig will be a bottleneck to production. There is a concern that secondary blasting may be required before cleaning can occur. This method will also be subject to the risk of higher dilution considering the lack of control on the long hole drilling.

In terms of viability scalability and flexibility, this mining method is very similar to underhand stoping.





Mining method modelled

Technical Feasibility Economic Viability

4 Trench or slot Bauer cutter

This method is limited. A single machine is utilised which significantly restricts production. The method requires significant technical support and is subject to low levels of availability. Production levels are lowest of all of the surface mining methods considered.

This method is not economically viable in so far as that positive cash flow is realized only in year four of a seven year operating period.


To this method being a hybrid of shallow open pit and shallow trench mining is technically feasible

This method has an NPV nominally less than what can be achieved from the CESS only. It is therefore economically unattractive.

Table 6-1: Qualitative comparisons of options The Slot 2 Bench Mining option is considered to be the preferred solution from the perspectives of financial returns, ease of mining, safety, and the ability to potentially continue to a deeper level if required. The potential to accelerate this option was looked at in the financial model. Table 6-2 indicates the effect on the NPV and IRR.

Option Years earlier NPV @10% IRR % Based Case 0 $33 340 000 43% Option A 3 $20 628 000 28% Option B 2 $24 165 000 32%

Table 6-2: Accelerated option effect on NPV and IRR

There is clearly no reason to try to start the surface mining earlier since, whilst it is economical within itself and generates early production, it still requires a large percentage of the total project capital early in the project and does not provide adequate cash flows to make this option financially attractive.





7. RECOMMENDATION The financial modelling and the qualitative assessment of the various potential surface mining options indicate that the preferred solution is manual slot bench mining. The valley open pit option is considered to be the easiest technical solution, but is effectively rendered unattractive by the large mining equipment capital expenditure. If this can be alleviated by the purchase of second hand or utilising existing equipment, then this may merit further investigation as well. This option, being the only mechanised one, could also be used as a benchmark for comparison against the manual slot bench mining proposed. The best financial returns are obtained by commencing with the surface mining and the underground development at the same time.





8. ANNEXURES

Discussion on mining method 12 As this method was not reflected in the NFTR of the brainstorming session, it is reproduced here.

Reef drive

Crown Pillar

Vertical Shaft

(Thermal Spalling)

Surface

Drill and blast from

surface

Fissure

150m25

m

2m The method involves the following sequences: • Create shallow vertical shafts at about 150m centres using a combination of thermal

spalling and blasting. The thermal spalling is a method advanced by Maxem and utilises heat from diesel fired burners lowered in pre-drilled holes

• Create reef drives linking the vertical shafts (pits) • Drill and blast from surface • Transport to the vertical shafts • Hoist using a method already explored (frame with kibble)

The method appears in the qualitative evaluation.





Communication with Bauer: the Trench Cutting Investigation Discussions were held with Lars Roesler, Area Manager (Africa) for Bauer in South Africa on the 10th of June 2014. The discussions concerned the use of the Bauer Trench Cutter and Grab technologies for mining of the kimberlite dyke. Technical documentation in the form of brochures is available for these technologies. Bauer currently utilises these systems in the civil engineering environment for the excavation of cut off and diaphragm walls, and for intersecting groundwater and constructing foundations. There has to date been very limited application of the technology in the mining space. Where it has been used, it has been for bulk sampling and not for primary mining activity. Bauer also offers RC sampling drilling, utilised exclusively for exploration purposes.

8.2.1. General notes The following notes refer to both the Cutter and grab systems: • Cutting or grabbing at an inclination is possible. The body of the Cutter has 12

hydraulic pads that can be adjusted to force the Cutter off vertical as required • If inclination is required, then the steel cables that support the Cutter as well as the

pumping pipe will have to be supported at surface to prevent them snagging on the hanging wall when the Cutter reaches a specific depth

• 800 X 2800 is the most popular cross section. A range is available (refer Bauer brochures on this topic)

• The first three metres of the slot should be excavated by alternative methods. This will provide a guide for the body of the Cutter as it commences operations. Alternatively concrete guide walls can be constructed on surface

• For hard country rock such as granite, a specific Cutter head should be used. Alternatively the rock could be pre-fractured by blasting from surface and excavated using the grab system

• Under normal conditions the size fraction that results from cutting is less than 50 mm (the suction pipe is 150mm)

• Contiguous mining is possible as the Cutter wheels rotate in opposite directions towards the middle. The Cutter wheels are able to be independently rotated which means that lateral movement of the Cutter body can be achieved by differential speeds being applied to the Cutter wheels

• The plant can be dismantled for transportation purposes. Disassembled sizes and loads are available for in various models of Cutter or Grab

• Trackless and mobile support equipment would include: o Mobile crane to assist in the assembly of the Cutter or Grab o Excavator for cleaning out the blasted starter trench o Front-End loader to move the material from the Desander plant (screening

and dewatering) to the conveyor or bin feeding the plant • As the Cutter or Grab moves along the dyke the Desander plant remains static up to

a distance of 500 m from the Cutter before it requires relocation (a mobile Desander plant is available)





• The advantages/disadvantages of the Grab system o Rate of advance is faster than the Cutter system o The grab system is dry but yields a larger fraction size then the Cutter System o The equipment is smaller which would result in associated lower setup costs o Side wall support – need to check whether the blasting required for the grab

system means more support than using the Cutter System o With pre-fracturing, a greater rate of advance can be achieved with the Grab o The expected advance rate for the Cutter System is 40 metres per day based

on a 16 hour day o Using the two systems together, alternate panels can be cut with the Cutter

System, and the remaining panels blasted and cleaned using the Grab. This means that the blasting is done with two open faces available, and cleaning is facilitated (however, the cutter or grab units are very expensive pieces of equipment, so testing the viability of using both together would be important)

8.2.2. Sierra Leone Learnings

Bauer has utilised its Cutter Technology on a diamond project in Sierra Leone. This deployment, during 2011, was considered unsuccessful. Over a six month period, only 40 metres of advance was achieved – at an average rate of cut of 0.5m per hour. From a Bauer perspective, some of the reasons why this endeavour was not successful include:

A second hand machine (CBC 33) was sourced from Singapore. Availability of the machine was poor due to frequent breakdowns The type of machine used was inappropriate. The base carrier was a compact version more suitable for urban deployment – movement around the dyke was limited. The carrier almost stood on the dyke, restricting access Geological mapping was poor – the limited work performed by the Cutter unit was predominantly in the granite country rock with little intersection of the kimberlite – sometimes up to 90% of the cut was in country rock





The Cutter unit (RSC C403 chisel) was not suitable for the country rock encountered – wear was excessive – the Roller Bit Cutter should have been used

Site preparation was not suitable. The cutting machine requires a level platform which was not provided The infrastructure support was not adequate in terms of power, water supply and pumping etc. These facilities were to be provided by the client. It is Bauer’s view that in future deployment, it should be on a contract mining basis, where Bauer will supply all the supporting services and infrastructure as relates to water and power and logistics – split responsibility should be avoided. The client would still be depended on for staffing support, such as the accommodation camp and its facilities. Logistics had been problematic – “obtaining spare parts was a nightmare”

Communication with Koidu The following is a response received from Dino Coutinho, previously employed by Koidu.

Looking at the information provided by Lars, the summary is pretty accurate. There were a number of problems with the programme; 1. The reconditioned CBC 33 sourced from Singapore proved to be the wrong option, the unit itself had some mechanical issues and although being compact it lacked flexibility in that it had a short reach between the machine platform itself and the cutting head. Taking into account the weight of the machine and having to position it so close to the collar of the trench for one. I felt that an operating platform with a lattice boom arrangement would offer more flexibility, for example the Bauer MC128HD. 2. There were a number of logistical issues related to both coordination of split responsibilities as well as securing short lead times on spares replacement.





3. With regard to the level of geological information required, we provided what we could at the time but the more info the better. It is important to have accurate data on the geological emplacement of the dyke/s (accurate mapping of the vertical dip for example), the in-situ dilution, compressive strengths and cut-abilty characteristics of the country rock and kimberlite. The more core sampling and delineation drilling the better. A generous amount of country rock and kimberlite samples (say +10mm to -150mm) should also be secured for accurate testing. 4. I would agree that a contract mining approach with performance guarantees would be most likely to succeed and will do away with the tendency for parties to engage in finger pointing when results are not achieved. The important thing to note is that although there were numerous problems, in my mind it has been proven that the trench cutter technology can be applied to kimberlite dyke/fissure mining. We have identified a number of possible solutions to the problems encountered with the trial, amongst others for example; pre-conditioning of the ore body (drill & blast) and subsequent extraction by mechanical or hydraulic grab.

Should it be decided that the Bauer Trench Cutter or grab technologies should be taken into the next phase of study, Dino Coutinho, now a free agent and no longer working for Koidu, is available to participate as required. The following paragraph extracted from his e-mail illustrates this:

I am happy to provide you with this oversight off the top of my head. As I mentioned on the phone, I have a wealth of knowledge, experience and access to detail in respect of this subject matter and I am in a unique position to add value to your study and any further developments thereof, should you require a more detailed analysis.

Trip report to Mauritius to view the Bauer technology A site visit was conducted at the Bagatelle dam in Mauritius where the Bauer Trench Cutter technology is being applied. The application on this dam site is for a 800mm wide concrete cut off wall approximately 25 -30 m deep under the full length of an earth embankment dam with a concrete spillway section in the middle. The purpose of the wall is to ensure that water from the dam once complete and filled, does not permeate through the substrates under the dam and results in water losses.





The approximate total length of the cut off wall is 2000m. In the central section, where the hard (200mpa) basalt is encountered, the cut off wall is approximately 800m long in plan. The reason for investigating this particular site where the Bauer Trench Cutter technology is being employed is because it reasonably replicates the Sierra Leone conditions that will be encountered. The similarities are summarised: • Hardness of country rock (200Mpa basalt – 170Mpa granite in Sierra Leone) • Contiguous cutting for a width of 800mm • Depth of cutting is similar (25-30m) • Wet conditions – high rainfall • “Strike” length – about 2km • Cutting machine – BC40 with RSC





BC 40 set up with the MC 128 base carrier BC 40

BC40 cutter head with RSC – chisels being replaced





The fundamental differences of this application as opposed to mining are summarised: Item Dam Construction Mining Inclination Consistent Verticality Inclined at 80deg to the horizontal Linearity Minimum deviation from the vertical Rate of change of inclination with

depth is a factor Use Cut off wall – slot filled with “waterproof”

concrete. Material emanating from the cutting operation is waste

Material emanating from the cutting operation is ore

Material Single Material - Basalt Dual Material – granite and Kimberlite

Driver Minimum cost but no business case required – no revenue applicable

Business case important - revenue /cost relationship

The construction sequence broadly entails: • Construct Guide walls • Cut three panels (2 X 3.2m outer panels first with center cut next) to yield 8m

primary cut • Repeat for adjacent primary 8m panel • Clean both panels under “working” bentonite, replacing with fresh bentonite • Trammie concrete in both panels displacing bentonite • Cut (secondary) between primary panels (in the process cutting through edges of

primaries) • Trammie concrete into the secondary cut slot

A similar construction sequence (without the concreting) has been adopted for the Bauer Trench Cutting mining option. Cut material is sent to the Desander Plant where dewatering occurs yielding the following “waste” products: • Coarse waste +65mm • Fine waste +15 -65mm • “Sand” +.6 -15mm • “Rock powder” – dust is generated when the cutter malfunctions • Water – principally contaminated bentonite – treated and returned

Bentonite is used: • In areas where side wall stability is required when cutting through less competent

material (as will be encountered in the construction of the cut off wall for the earth embankment sections)

• To facilitate flowability of the rock chips in suspension. Bauer contends that without Bentonite (water only) the lines transporting the waste rock chips to the desander plant would get blocked (particularly in the area where the waste line is coiled on the cutting machine





Note: it will be important to ascertain the impact on the processing plant of the presence of Bentonite in the rock chips reporting to the plant. The current view held by Bauer (South Africa) is that Bentonite will not be required. It is not a view held by the Bauer site team. Observations on site: • The production rate on average is 15 000tpa – extrapolated based on actual

performance achieved in the central hard rock section. • The rule of thumb production rate is 300mm/hour and includes for plant availability,

set up times etc. availability is estimated to be no more that 50%. • Work on site is 24/6, with two 12 hour shifts. Shift change over is on a “hot seat”

basis • Staff complement is 54 day shift and 28 night shift. Ratio of skilled (Bauer

personnel) to unskilled (principally local labour is 1:1 as negotiated with the Mauritius government)

• At times, when advance rate is slow, impact chisels are judiciously used to weaken the rock before the cutter is again utilised

• The following is a table developed off the site records and reflects the anticipated production in the hard rock condition

• Fuel consumption – 1000litres diesel/machine/shift • The Desander machine – 1000kva – allowance for all pumping and plant operation • Considerable number of chissels being broken (50 in 1.5m advance while on site)

The following was offered by Thomas Stocker gleaned from his experience on the Koidu project in Sierra Leone, as a suitable site setup for this mining application. • BC40 with MC96 base carrier (HTS 50) • Use bentonite to prevent blockage in the slurry lines • RBH35 – agitator box • A liberal supply of spares and tools (a well-stocked workshop) • Comprehensive preparation associated with the guide walls • Desander on trailer (BE475) • The guide frame to be mechanically bolted to the guide walls (not hydraulic)





Note for the record – brainstorming session

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Updated Tongo Resource

NOT FOR DISTRIBUTION IN THE UNITED STATES OR FOR DISSEMINATION TO US NEWS WIRE SERVICES.

XX November 2014

Draft 7

AIM: STEL

Stellar Diamonds plc

(“Stellar” or the “Company”)

35% Increase in Resource & Diamond Grade at Tongo K imberlite Dyke Project

Stellar Diamonds plc, the London quoted (AIM: STEL) diamond development company focused on West

Africa, is pleased to announce an updated resource estimate for its 100% owned high grade Tongo kimberlite

Dyke-1 project in eastern Sierra Leone.

Highlights:

• 35% increase in JORC compliant inferred resource to 1,447,000 carats for Dyke-1

• Bulk sampling results have led to a 37% increase i n average diamond grade to 165 carats per

hundred tonnes

• Grade and resource increase underpins expected exce llent project economics

• Diamond price models of $145 and US$270 per carat

• In-situ kimberlite value estimated at between US$23 9 and US$324 per tonne

• In-situ resource value of US$214 million to US$290 million

• Surface and underground mining study to be announce d in the near future

• Additional value potential from further dykes withi n the project

Chief Executive Karl Smithson commented:

“The combination of high grades and high diamond values make this kimberlite one of the highest value

kimberlites in the world in terms of in-situ value of dollar per tonne. The significant increase in the diamond

grade and resource for Dyke-1 to 1.45 million carats is an extremely positive step in the development of this

high grade and high value per tonne diamond asset.

“Importantly further resource potential exists from three parallel kimberlite dykes which form part of the Tongo

dyke swarm. This includes the 1km long Dyke-4 which has previously been bulk sampled and returned a

diamond grade estimate of 110cpht and an estimated average diamond value of US$140 per carat.

“Consistent with our focused strategy of accelerating our key kimberlite projects through the development

pipeline and into production, as evidenced by the recent commencement of trial mining at our Guinean Baoulé

project, a study into surface and underground mine development at Tongo is being finalised. In line with this

we are currently re-calculating our financial model to reflect the resource upgrade and mine plan and I look

forward to updating shareholders with our progress in the near future.”

Updated Resource Statement

Independent consultant CAE Mining has updated the maiden JORC compliant resource statement based on

the recently completed bulk sampling and diamond grade and value modelling. The volume and tonnage of

the previously announced resource statement (3 December 2012) remain at 321,000m3 and 895,000 tonnes

respectively, to a depth of 300m. No additional drilling or microdiamond sampling was conducted during this

phase of work and all previous data and models, including the bulk sampling from 2012, were used to

complement the new data.

The following new bulk sampling and valuation data were utilised in calculating the revised resource:

• 2014 bulk sampling of 645 dry tonnes of kimberlite which yielded 1,182 carats at a 1mm cut-off

• Four independent valuations of the 1,182 carats of diamonds that were exported to Antwerp were

used in the revised diamond modelling exercise

• Sieving analysis and diamond valuations were all incorporated into new diamond grade and value

models

Diamond Size Distribution and Grade Model

Two diamond grade models have been established based on log-probability graphs using the available

microdiamond and bulk sampling data. The microdiamond modelling (2012) suggests an average grade of

120cpht (in undiluted kimberlite), whereas the combined bulk sampling data (2012 and 2014) suggests an

increased average grade of 165cpht (in undiluted kimberlite), which is consistent with the actual higher

average grade yielded in 2014 of 183cpht. However, the higher grade model is also the result of a higher

proportion of smaller diamonds recovered when compared to that expected using the microdiamond grade

model. The disparity between the two models is due to a lower than expected number of stones between 2

and 10 carats based from the two phases of bulk sampling versus the microdiamond grade model. This could

be natural stone size distribution or more probably a result of the sample size being too small to recover the

expected larger stones. However, the microdiamond size distribution model suggests that the larger stones

should be present in the diamond population yielded by the bulk sampling and therefore a coarser size

distribution is to be expected.

Diamond Value Estimation

The diamond value was modelled using the 1,182 carats produced from the bulk sampling (1,168 carats after

acid cleaning). Four independent diamond marketing groups valued the diamond parcel. One group seems

to have undervalued the smaller diamonds relative to the other three groups. Diamond values of up to

US$3,200 per carat were given for a single stone of 6.7 carats in size. Most valuations per sieve size were

higher for the 2014 data compared to the 2012 data, as would be expected for both the valuations and the

subsequent modelled diamond values.

These four diamond valuations were combined and modelled to simulate the likely diamond value in a full

production parcel. Two price-size models were calculated along with the two size distribution (grade) models.

The diamond value model for the higher 165cpht grade has a modelled diamond value of US$145 per carat

as expected by a finer diamond size distribution. However, the coarser diamond size distribution as

calculated by the microdiamond model suggests a diamond value of US$270 per carat. If the “missing” larger

stones, as indicated from the diamond grade model, do appear in the run of mine production, then there is

considerable upside in diamond content and average price if the diamond size distribution turns out to be

coarser than suggested by bulk sampling, and the higher bulk sample grades are sustained.

A summary of the updated inferred resource at a +1.0mm cut off is given in Table 1 below, both as a lower

grade and higher grade model and is reported according to JORC (2012):

Tongo Dyke-1 Resource

Dec-12

Resource

Nov-14

Lower grade

model

Resource

Nov-14

Higher grade

model

Tonnes 895,000 895,000 895,000

Grade (cpht) +1.0mm cut-off 120 120 165

Carats in resource 1,074,000 1,074,000 1,447,000

Diamond Value (US$/ct) 248 270 145

$ per tonne in-situ at average value 297 324 239

Contained Value US$ million 266 290 214

Future Resource Potential

The Directors believe there is additional resource potential from Dyke-1 and other kimberlites in the licence

area, as follows:

• Deeper drilling of Dyke-1, to depths of up to 700m in line with kimberlite dykes mined in South Africa;

• Resource drilling of the 1km long Dyke-4, which has a bulk sampled grade of 110cpht and diamond

value of US$140 per carat. However, the diamond parcel amounts to 91 carats, which is not a

representative size;

• Resource drilling of the 800m long Dyke-2 and 500m long Dyke-3. Kimberlite samples of 200kg each

have previously been processed for the recovery of microdiamonds. These samples yielded

abundant diamonds which suggested modelled +1mm diamond grades of 140cpht and 185cpht for

Dykes-2 and 3 respectively.

The Tongo resource statement report will be lodged on the Company’s website at www.stellar-diamonds.com.

This announcement has been reviewed by Karl Smithson, Chief Executive of Stellar, a qualified geologist and

Fellow of the Institute of Materials, Metals, Mining, with 26 years' experience.

Ebola Update

The Company is encouraged by the support given to Sierra Leone by the British Government and the various

NGO’s who are tackling the Ebola virus on a daily basis. Although the number of cases is increasing in the

west of the country it is encouraging to note that there have been no new cases in the Kenema and Tongo

areas for over one month, which would suggest that the virus is now contained and under control in the

project area. The Company believes that as the capacity to treat the affected increases so the virus will be

contained throughout the country and eventually eradicated.

About Stellar Diamonds plc

Stellar is an AIM quoted (AIM: STEL) West African focused diamond development company which has

commenced trial mining of its Baoulé kimberlite in Guinea, and is progressing the 1.5 million carat Tongo

Dyke-1 resource in Sierra Leone through a definitive feasibility study. In addition, Stellar holds the 3 million

carat Droujba project in Guinea and continues to pursue diplomatic channels to ensure the proper

reinstatement of its Kono licences in Sierra Leone.

** ENDS **

For further information contact the following or visit the Company’s website at www.stellar-diamonds.com.

Karl Smithson, CEO

Philip Knowles, CFO



Tel: +44 (0) 20 7010 7686

Tel: +44 (0) 20 7010 7686

Emma Earl

Colin Rowbury

Daniel Stewart & Company plc

(Nomad/Broker)

Tel: +44 (0) 20 7776 6550

Tel: +44 (0) 20 7776 6550

Lottie Brocklehurst St Brides Media & Finance Ltd Tel: +44 (0) 20 7236 1177

Hugo de Salis (Financial PR) Tel: +44 (0) 20 7236 1177





Financial model (Base Case)

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)INPUTS


Currency Heading 1 ZARCurrency Heading 2 US$Currency Total Line 1 TOTAL ZARCurrency Total Line 2 TOTAL US$

2 DTS 1 - SURFACE SLOT 1: UNDERHAND STOPINGDTS 2 - SURFACE SLOT 2: BENCH STOPINGDTS 3 - SURFACE SLOT 3: LONG HOLE DRILLING STOPING

STELLAR DIAMONDS DTS OPTION DTS 4 - TRENCH CUTTERTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE) DTS 5 - HYBRID OPEN OPITFINANCIAL MODEL DTS 6 - CESSUS$

YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$

MINING Surface MiningWaste t - 0 0 0 0 0 0 0 0 0 0 0 0 0Ore Mined t 327 240 75 636 133 475 118 129 0 0 0 0 0 0 0 0 0 0Carats Mined cts 120 528 27 469 48 475 44 583 0 0 0 0 0 0 0 0 0 0Underground MiningDecline Waste t - 0 0 0 0 0 0 0 0 0 0 0 0 0Shaft Waste t 26 669 12 251 12 528 1 890 0 0 0 0 0 0 0 0 0 0Metres Developed m 43 987 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806Total Waste Mined t 307 490 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327Ore Mined t 1 116 014 0 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486Carats Mined cts 676 612 0 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351Total MiningWaste t 26 669 12 251 12 528 1 890 0 0 0 0 0 0 0 0 0 0Ore Mined t 1 443 254 75 636 146 306 163 136 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486Carats Mined cts 797 140 27 469 56 112 71 623 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351REVENUERevenue Per Carat $ 270 270 270 270 270 270 270 270 270 270 270 270 270 270Project Revenue $000's 215 228 7 417 15 150 19 338 11 224 14 264 17 706 21 148 24 538 24 909 19 449 15 680 15 400 9 005TOTAL COSTS $000's 135 356 19 551 14 042 12 670 7 876 8 877 8 706 9 782 10 981 10 737 9 189 8 464 8 265 6 217Total Working Costs $000's 114 299 7 383 12 204 11 237 7 405 7 823 8 082 8 999 10 162 10 249 8 669 8 252 8 151 5 683Head Office $000's 780 60 60 60 60 60 60 60 60 60 60 60 60 60Underground Mining (CESS Mining Only) $000's - - - - - - - - - - - - - -Surface Mining (including CESS U/G Mining) $000's 64 381 3 330 6 564 7 615 3 696 4 350 4 519 5 119 5 930 5 996 4 934 4 765 4 692 2 870Plant $000's 1 570 90 176 57 85 105 127 152 176 178 139 112 110 63Engineering $000's 12 211 992 1 620 673 764 828 899 983 1 063 1 063 937 850 845 696Security $000's 361 28 28 28 28 28 28 28 28 28 28 28 28 28Manpower $000's 13 241 1 465 1 571 1 571 1 359 888 799 799 799 799 799 799 799 799Infrastructure $000's 3 955 228 228 228 228 269 326 389 451 456 356 287 283 228Logistics $000's 2 713 163 302 126 165 199 206 233 268 270 224 211 209 136Environmental $000's 824 63 63 63 63 63 63 63 63 63 63 63 63 63Contingency $000's 14 262 963 1 592 815 956 1 034 1 054 1 174 1 325 1 337 1 131 1 076 1 063 741Cost Per Tonne Treated $/t 79 - 83 69 108 89 74 69 68 68 73 86 86 106Total Capital Expenditure $000's 21 058 12 168 1 838 1 433 471 1 054 624 783 819 488 520 212 113 534Head Office $000's 10 10 - - - - - - - - - - - -Underground Mining (CESS Mining Only) $000's - - - - - - - - - - - - - -Surface Mining (including CESS U/G Mining) $000's 5 782 2 632 1 258 790 165 222 168 311 235 - - - - -Plant $000's 3 214 3 214 - - - - - - - - - - - -Engineering $000's 2 472 2 472 - - - - - - - - - - - -Security $000's 213 213 - - - - - - - - - - - -Infrastructure $000's 1 557 1 557 - - - - - - - - - - - -Logistics $000's 360 360 - - - - - - - - - - - -Environmental $000's 537 98 - - - - - - - - - - - 439Major replacement $000's 4 120 1 319 456 244 694 375 370 477 424 452 185 98 25Contingency $000's 2 794 1 612 262 187 61 137 81 102 107 64 68 28 15 70Notional Profit (000's) (12 134) 1 109 6 668 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788

IRR 43%NPV @ 5% $51 259NPV @ 7.5% $41 294NPV @ 10% $33 340NPV @ 12.5% $26 943

TOTALUNITNOTIONAL PROFIT

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARY ***SURFACE SLOT 1: UNDERHAND STOPING

MINING UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t - - - - - - - - - - - - - - Fissure Mined per Pit t 11 902 11 902 11 902 - Ore Mined per Pit t 39 325 39 325 39 325 - - - - - - - - - - Number of Pits No 2 3 2 - - - - - - - - - - Total Fissure Mined t 20 233 35 706 19 391 - 75 330 Total Ore Mined t 66 853 117 976 60 601 - - - - - - - - - - 245 430 Carats Recovered cts 24 280 42 847 23 270 - - - - - - - - - - 90 396 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - Shaft waste tonnes t 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - 1L diluted ore tonnes t - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Total carats cts - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 Total diluted ore tonnes t 66 853 130 807 105 607 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 Total carats cts 24 280 50 484 50 310 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 Underground Mining Cost per ore tonne US$/t 54 54 54 54 50 42 40 40 40 42 50 50 54 54Surface Mining Costs US$/t 42 42 42 42 - - - - - - - - - Surface Materials Handling US$/t 2 2 2 2 - - - - - - - - - Mining Operating cost US$ 2 943 103 5 882 184 5 082 834 3 696 280 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 60 779 666

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING CAPEXSURFACE SLOT 1: UNDERHAND STOPING

YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13 TOTALZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR

SURFACE MININGUnderground Infrastructure 0 0Vertical Access 1 627 316 1 627 316Mining Equipment 3 849 300 3 849 300Surface Facilities 2 693 436 2 693 436SURFACE MINING SUB TOTAL 8 170 052 0 0 0 0 0 0 0 0 0 0 0 0 8 170 052SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 27 987 425 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 60 269 771TOTAL US$ 2 730 480 1 257 744 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 5 879 978

MINING CAPEX SUMMARYITEM

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING OPEXSURFACE SLOT 1: UNDERHAND STOPING

MINING UNIT VALUEStrike Length m 2 000 Dyke Width m 0.45 Mining depth m 30 Total fissure volume in situ m³ 27 000 Ore Density t/m3 2.79 Total fissure tonnes in situ t 75 330 Dyke Grade cpht 120 Total carats in situ cts 90 396 Stope width m 1.5 Waste Density t/m3 2.70 Total waste in situ t 170 100 Total ore mined t 245 430 Monthly horizontal stope advance m 10 Ideal stope face angle ° to horizontal 45 Average stope length m 42 Mining Recovery % 98%Fissure tons per stope per month t 522 Tons waste per stope per month t 1 203 Mining Efficiency % 95%Fissure tons per stope per month t 496Total tons per stope per month t 1 639 Total tons per stope per annum t 19 663 Number of stopes per pit No 2 Fissure tons per pit per annum t 11 902 Total tons per pit per annum t 39 325

MINING OPEX UNIT 2002 2008 2012 2014 �

Stoping: 1m width ZAR 180 255 322 362Stoping fixed component % 60% 60% 60% 60%Stoping fixed component ZAR 108 153 193 217Stoping variable component % 40% 40% 40% 40%Stoping variable component ZAR 72 102 129 145Stoping cost ZAR 216 306 387 435Stoping cost US$ 21 30 38 42

Average RSA CPI 6%

PLANT OPEX UNIT Y1 Y2 Y3 TOTALSurface tonnes treated t 66 853 117 976 60 601 245 430Unit cost per tonne treated ZAR/t 12 12 12 12Surface plant costs ZAR 802 238 1 415 715 727 207 2 945 160CESS plant costs ZAR 19 634 201 090 587 203 807 928

TOTAL PLANT COSTS ZAR 821 873 1 616 805 1 314 410 3 753 088TOTAL PLANT COSTS US$ 80 183 157 737 128 235 366 155

ENGINEERING OPEX UNIT Y1 Y2 Y3 TOTALSurface tonnes treated t 66 853 117 976 60 601 245 430Engineering costs per tonne treated US$/t 8 8 8 8Surface engineering costs US$ 534 826 943 810 484 804 1 963 440CESS engineering costs US$ 386 814 552 038 672 571 1 611 423

TOTAL ENGINEERING COSTS US$ 921 639 1 495 848 1 157 375 3 574 863

MANPOWER OPEX UNIT Y1 Y2 Y3 TOTALCESS manpower costs US$ 427 152 1 571 024 1 571 024 3 569 201Additional surface manpower costs US$ 1 038 000 0 0 1 038 000

TOTAL MANPOWER COSTS US$ 1 465 152 1 571 024 1 571 024 4 607 201

LOGISTICS OPEX UNIT Y1 Y2 Y3 TOTAL3.5% of Opex US$ 163 370 301 553 301 032 765 954

OPEX CONTINGENCY UNIT Y1 Y2 Y3 TOTAL15% of Opex US$ 962 946 1 591 770 1 563 260 4 117 976

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARY ***SURFACE SLOT 2: BENCH STOPING

MINING UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t - - - - - - - - - - - - - - Fissure Mined per Pit t 13 465 13 465 13 465 - Ore Mined per Pit t 44 492 44 492 44 492 - - - - - - - - - - Number of Pits No 2 3 3 - - - - - - - - - - Total Fissure Mined t 22 891 40 396 37 153 - 100 440 Total Ore Mined t 75 636 133 475 118 129 - - - - - - - - - - 327 240 Carats Mined cts 27 469 48 475 44 583 - - - - - - - - - - 120 528 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - Shaft waste tonnes t 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - 1L diluted ore tonnes t - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Carats Mined cts - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t 75 636 146 306 163 136 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 443 254 Total carats cts 27 469 56 112 71 623 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 797 140 Underground Mining Cost per ore tonne US$/t 54 54 54 54 50 42 40 40 40 42 50 50 54 58Surface Mining Costs US$/t 42 42 42 42 - - - - - - - - - Surface Materials Handling US$/t 2 2 2 2 - - - - - - - - - Mining Operating cost US$ 3 329 741 6 564 486 7 615 445 3 696 280 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 64 381 217

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING CAPEXSURFACE SLOT 2: BENCH STOPING


SURFACE MININGUnderground Infrastructure 0 0Vertical Access 1 627 316 1 627 316Mining Equipment 2 840 175 2 840 175Surface Facilities 2 693 436 2 693 436SURFACE MINING SUB TOTAL 7 160 927 0 0 0 0 0 0 0 0 0 0 0 0 7 160 927SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 26 978 300 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 59 260 646TOTAL US$ 2 632 029 1 257 744 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 5 781 526


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING OPEXSURFACE SLOT 2: BENCH STOPING

MINING UNIT VALUEStrike Length m 2 000 Dyke Width m 0.45 Mining depth m 40 Total fissure volume in situ m³ 36 000 Ore Density t/m³ 2.79 Total fissure tonnes in situ t 100 440 Dyke Grade cpht 120 Total carats in situ cts 120 528 Stope width m 1.50 Waste Density t/m³ 2.70 Total waste in situ t 226 800 Total ore mined t 327 240 Monthly horizontal face advance m 12 Ideal stope face angle ° to horizontal 90 Average Stope Length m 40 Mining Recovery % 98%Fissure tons per stope per month t 591 Tons waste per stope per month t 1 361 Mining Efficiency % 95%Fissure tons per stope per month t 561Total tons per stope per month t 1 854 Total tons per stope per annum t 22 246 Number of stopes per pit No 2 Fissure tons per pit per annum t 13 465 Total tons per pit per annum t 44 492

MINING OPEX UNIT 2002 2008 2012 2014 �


Average RSA CPI 6%

PLANT OPEX UNIT Y1 Y2 Y3 TOTALSurface tonnes treated t 75 636 133 475 118 129 327 240Unit cost per tonne treated ZAR/t 12 12 12 12Surface plant costs ZAR 907 629 1 601 699 1 417 552 3 926 880CESS plant costs ZAR 19 634 201 090 587 203 807 928


ENGINEERING OPEX UNIT Y1 Y2 Y3 TOTALSurface tonnes treated t 75 636 133 475 118 129 327 240Engineering costs per tonne treated US$/t 8 8 8 8Surface engineering costs US$ 605 086 1 067 799 945 035 2 617 920CESS engineering costs US$ 386 814 552 038 672 571 1 611 423


MANPOWER OPEX UNIT Y1 Y2 Y3 TOTALCESS manpower costs US$ 427 152 1 571 024 1 571 024 3 569 201Additional surface manpower costs US$ 1 038 000 0 0 1 038 000




STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARY ***SURFACE SLOT 3: LONG HOLE DRILLING STOPING

MINING UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t - - - - - - - - - - - - - - Fissure Mined per Pit t 12 624 12 624 12 624 - - - - - - - - - - - Ore Mined per Pit t 41 711 41 711 41 711 - - - - - - - - - - - Number of Pits No 2 3 3 - - - - - - - - - - - Total Fissure Mined t 21 460 37 871 15 998 - - - - - - - - - - 75 330 Total Ore Mined t 70 909 125 133 49 389 - - - - - - - - - - 245 430 Carats Recovered cts 25 753 45 446 19 198 - - - - - - - - - - 90 396 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - Shaft waste tonnes t 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - 1L diluted ore tonnes t - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Total carats cts - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 Total diluted ore tonnes t 70 909 137 963 94 395 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 Total carats cts 25 753 53 083 46 238 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 Underground Mining Cost per ore tonne US$/t 54 54 54 54 50 42 40 40 40 42 50 50 54 55Surface Mining Costs US$/t 46 46 46 46 - - - - - - - - - Surface Materials Handling US$/t 2 2 2 2 - - - - - - - - - Mining Operating cost US$ 3 352 452 6 604 564 4 750 022 3 696 280 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 61 578 584

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING CAPEXSURFACE SLOT 3: LONG HOLE DRILLING STOPING


SURFACE MININGUnderground Infrastructure 0 0Vertical Access 1 527 549 1 527 549Mining Equipment 6 910 313 6 910 313Surface Facilities 692 784 692 784SURFACE MINING SUB TOTAL 9 130 646 0 0 0 0 0 0 0 0 0 0 0 0 9 130 646SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 28 948 019 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 61 230 365TOTAL US$ 2 824 197 1 257 744 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 5 973 694


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING OPEXSURFACE SLOT 3: LONG HOLE DRILLING STOPING

MINING UNIT VALUEStrike Length m 2 000 Dyke Width m 0.45 Mining depth m 30 Total fissure volume in situ m³ 27 000 Ore Density t/m³ 2.79 Total fissure tonnes in situ t 75 330 Dyke Grade cpht 120 Total carats in situ cts 90 396 Stope width m 1.5 Waste Density t/m³ 2.70 Total waste in situ t 170 100 Total ore mined t 245 430 Monthly horizontal stope advance m 15 Ideal stope face angle ° to horizontal 90 Average stope length m 30 Mining Recovery % 98%Fissure tons per stope per month t 554 Tons waste per stope per month t 1 276 Mining Efficiency % 95%Fissure tons per stope per month t 526Total tons per stope per month t 1 738 Total tons per stope per annum t 20 855 Number of stopes per pit No 2 Fissure tons per pit per annum t 12 624 Total tons per pit per annum t 41 711

MINING OPEX UNIT 2014Stoping: 1m width ZAR 390Stoping fixed component % 60%Stoping fixed component ZAR 234Stoping variable component % 40%Stoping variable component ZAR 156Stoping cost ZAR 468Stoping cost US$ 46

Average RSA CPI 6%

PLANT OPEX UNIT Y1 Y2 Y3 TOTALSurface tonnes treated t 70 909 125 133 49 389 245 430Unit cost per tonne treated ZAR/t 12 12 12 12Surface plant costs ZAR 850 902 1 501 592 592 665 2 945 160CESS plant costs ZAR 19 634 201 090 587 203 807 928


ENGINEERING OPEX UNIT Y1 Y2 Y3 TOTALSurface tonnes treated t 70 909 125 133 49 389 245 430Engineering costs per tonne treated US$/t 8 8 8 8Surface engineering costs US$ 567 268 1 001 062 395 110 1 963 440CESS engineering costs US$ 386 814 552 038 672 571 1 611 423


MANPOWER OPEX UNIT Y1 Y2 Y3 TOTALCESS manpower costs US$ 427 152 1 571 024 1 571 024 3 569 201Surface manpower costs US$ 1 038 000 0 0 1 038 000




NOTESAdditional costs for long hole drilling

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARYTRENCH CUTTER

MINING UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t - - - - - - - - - - - - - - Total Ore Mined t - 16 083 16 083 16 083 16 083 16 083 16 083 16 083 - - - - - 112 581 Carats Recovered cts - 10 339 10 339 10 339 10 339 10 339 10 339 10 339 - - - - - 72 373 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - Shaft waste tonnes t 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - 1L diluted ore tonnes t - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Total carats cts - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 Total diluted ore tonnes t - 28 914 61 090 84 968 103 514 124 572 145 629 166 164 151 762 118 446 95 757 94 292 53 486 Total carats cts - 17 976 37 379 51 910 63 168 75 917 88 665 101 221 92 255 72 033 58 073 57 038 33 351 Underground Mining Cost per ore tonne US$/t 54 54 54 54 50 42 40 40 40 42 50 50 54 63Surface Mining Costs US$/t 420 420 420 420 - - - - - - - - - Surface Materials Handling US$/t - - - - - - - - - - - - - Mining Operating cost US$ - 7 443 314 9 169 835 10 451 121 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 70 239 536

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARYTRENCH CUTTER

PER MODULE UNIT VALUEPrimary Panels No 4Number of cuts per primary panel No 3Secondary panels No 3Number of cuts per secondary panel No 1Pillars No 1Number of cuts per pillar No 0Length of primary panel m 7Length of secondary panel m 2.4Length of pillar m 1.4Total length of module m 36.6Depth of cut m 25Width of cut m 0.8total length of cut m 375Rate of cutting m/hour 0.4hours per day hr 24Time to cut days 39Set ups No 15Time per set up hrs 1.5Total set up days No 0.9Total days No 40Advance on strike m/day 0.915Strike length m 2 000Total operating days No 2 186Working days per annum days 300Years of operation No 7.3Ore SG t/m³ 2.79Tonnes/day t 51Tonnes /annum t 15317Cutter width m 0.8Overbreak % 5%Mined width m 0.84Tonnes/annum t 16 083Dyke width m 0.45Mined grade cpht 64

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING CAPEXTRENCH CUTTER


SURFACE MININGMobilisation 8 820 000 8 820 000Cutter modifications 5 880 000 5 880 000Tools and equipment 6 020 000 6 020 000Cutter wheels 2 394 000 2 394 000Site establishment/dis-establishment 1 274 000 10 094 000 11 368 000Major overhaul 5 460 000 5 460 000SURFACE MINING SUB TOTAL 24 388 000 0 0 0 5 460 000 0 0 10 094 000 0 0 0 0 0 39 942 000SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 44 205 373 12 891 873 8 102 574 1 690 380 7 738 380 1 722 380 3 188 380 12 502 380 0 0 0 0 0 92 041 719TOTAL US$ 4 312 719 1 257 744 790 495 164 915 754 964 168 037 311 061 1 219 744 0 0 0 0 0 8 979 680


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING OPEXTRENCH CUTTER

OPEX UNIT VALUEBauer Proposal: all inclusive US$/t 420 TOTAL US$/t 420

PLANT OPEX UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 TOTALSurface tonnes treated t 0 16 083 16 083 16 083 16 083 16 083 16 083 16 083 112 581Unit cost per tonne treated ZAR/t 12 12 12 12 12 12 12 12 96Surface plant costs ZAR 0 192 995 192 995 192 995 192 995 192 995 192 995 192 995 1 350 968CESS plant costs ZAR 19 634 201 090 587 203 873 745 1 074 698 1 301 866 1 554 558 1 800 967 7 413 761

TOTAL PLANT COSTS ZAR 19 634 394 086 780 198 1 066 741 1 267 694 1 494 861 1 747 553 1 993 962 8 764 729TOTAL PLANT COSTS US$ 1 916 38 447 76 117 104 072 123 677 145 840 170 493 194 533 855 096

ENGINEERING OPEX UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 TOTALSurface tonnes treated t 0 16 083 16 083 16 083 16 083 16 083 16 083 16 083 112 581Engineering costs per tonne treated US$/t 8 8 8 8 8 8 8 8 8Surface engineering costs US$ 0 128 664 128 664 128 664 128 664 128 664 128 664 128 664 900 645CESS engineering costs US$ 386 814 552 038 672 571 764 405 827 540 899 286 982 511 1 062 866 6 148 030

TOTAL ENGINEERING COSTS US$ 386 814 680 702 801 234 893 068 956 204 1 027 950 1 111 175 1 191 530 7 048 676

MANPOWER OPEX UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 TOTALCESS manpower costs US$ 427 152 1 571 024 1 571 024 1 358 531 887 528 798 511 798 511 798 511 8 210 793Additional surface manpower costs US$ 1 038 000 0 0 0 0 0 0 0 1 038 000

TOTAL MANPOWER COSTS US$ 1 465 152 1 571 024 1 571 024 1 358 531 887 528 798 511 798 511 798 511 9 248 793

LOGISTICS OPEX UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 TOTAL3.5% of Opex US$ 163 370 301 553 301 032 168 053 195 275 206 474 233 434 267 642 1 836 834

OPEX CONTINGENCY UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 TOTAL15% of Opex US$ 962 946 1 591 770 1 563 260 967 343 1 018 380 1 054 150 1 173 735 1 325 474 9 657 059

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARYOPEN PIT

MINING UNIT Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t 941 218 892 257 434 416 286 797 - - - - - - - - - 2 554 688 Total Ore Mined t 50 400 50 400 24 996 21 084 - - - - - - - - - 146 880 Carats Recovered cts 29 484 29 484 14 623 12 334 - - - - - - - - - 85 925 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - Shaft waste tonnes t 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - 1L diluted ore tonnes t - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Total carats cts - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t 953 469 909 603 450 187 306 727 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 Total diluted ore tonnes t 50 400 63 231 70 003 89 969 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 Total carats cts 29 484 37 121 41 663 53 905 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 Underground Mining Cost per ore tonne US$/t 54 54 54 54 50 42 40 40 40 42 50 50 54 57Surface Mining Costs US$/t 5 5 5 5 - - - - - - - - - Mining Operating cost US$ 4 958 090 5 401 758 4 712 054 5 235 685 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 63 482 853

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING CAPEXOPEN PIT


SURFACE MININGPit Dewatering 116 893 116 893Mining Equipment 36 123 750 36 123 750Surface Facilities 520 189 520 189SURFACE MINING SUB TOTAL 36 760 832 0 0 0 0 0 0 0 0 0 0 0 0 36 760 832SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 56 578 205 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 88 860 551TOTAL US$ 5 519 825 1 257 744 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 8 669 322


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING OPEXOPEN PIT: 25m + TRENCH

TOTAL OPEN PIT UNIT VALUE OPEN PIT MINING UNIT VALUE TRENCH MINING UNIT VALUE PLANT OPEX UNIT Y1 Y2 Y3 Y4 TOTALStrike Length m 2 000 Strike Length m 2 000 Strike Length m 2 000 Surface tonnes treated t 50 400 50 400 24 996 21 084 146 880Dyke Width m 0.45 Dyke Width m 0.45 Dyke Width m 0.45 Unit cost per tonne treated ZAR/t 12 12 12 12 12Ore in Situ t 75 330 Pit Floor Width m 7.50 Width of Excavator Bucket m 1 Surface plant costs ZAR 604 800 604 800 299 952 253 008 1 762 560Carats in Situ ct 90 396 Ore depth m 25 Trench Depth m 5 CESS plant costs ZAR 19 634 201 090 587 203 873 745 1 681 673RoM Ore t 146 894 Slope Angle deg 65 Ore Density t/m3 2.79 TOTAL PLANT COSTS ZAR 624 434 805 890 887 155 1 126 753 3 444 233RoM Carats ct 85 876 Ore Density t/m3 2.79 Waste Density t/m3 2.70 TOTAL PLANT COSTS US$ 60 920 78 623 86 552 109 927 336 023RoM Grade ct/t 0.58 Waste Density t/m3 2.70 Ore in situ t 12 555 Total Waste t 2 626 253 Ore in Situ t 62 775 Mining Dilution % 100% ENGINEERING OPEX UNIT Y1 Y2 Y3 Y4 TOTALTotal RoM Waste t 2 554 689 Mining Dilution % 100% Mining Recovery % 95% Surface tonnes treated t 50 400 50 400 24 996 21 084 146 880Strip Ratio No 17.4 Mining Recovery % 95% RoM Ore t 24 482 Engineering costs per tonne treated US$/t 8 8 8 8 8Mining Cost US$/t 87 RoM Ore t 122 411 Total Waste t 14 850 Surface engineering costs US$ 403 200 403 200 199 968 168 672 1 175 040Mining Cost US$ 13 507 914 Waste: Sides t 1 573 788 Total RoM Waste t 2 923 CESS engineering costs US$ 386 814 552 038 672 571 764 405 2 375 827

Waste: Ends t 25 114 Carats in Situ ct 15 066 TOTAL ENGINEERING COSTS US$ 790 014 955 238 872 539 933 077 3 550 867Waste: Pit Floor t 1 012 500 RoM Carats ct 14 313 Total Waste t 2 611 403 RoM Grade ct/t 0.58 MANPOWER OPEX UNIT Y1 Y2 Y3 Y4 TOTALTotal RoM Waste t 2 551 766 CESS manpower costs US$ 427 152 1 571 024 1 571 024 1 358 531 4 927 732Strip Ratio No 20.8 Additional surface manpower costs US$ 1 038 000 0 0 0 1 038 000Mining Cost US$/t 5 TOTAL MANPOWER COSTS US$ 1 465 152 1 571 024 1 571 024 1 358 531 5 965 732Carats in Situ ct 75 330 RoM Carats ct 71 564 LOGISTICS OPEX UNIT Y1 Y2 Y3 Y4 TOTALRoM Grade ct/t 0.58 3.5% of Opex US$ 163 370 301 553 301 032 168 053 934 008Mining Cost US$ 13 370 889

OPEX CONTINGENCY UNIT Y1 Y2 Y3 Y4 TOTAL15% of Opex US$ 962 946 1 591 770 1 563 260 967 343 5 085 319

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING SUMMARYDTS 6 - CESS

Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalDecline waste tonnes t 5 279 554 - - - - - - - - - - - 5 832 Shaft waste tonnes t 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t 1 636 3 927 982 3 927 2 127 - - - - - - - - 12 599 0L bulk sample carats cts 603 1 446 1 446 1 446 783 - - - - - - - - 5 725 1L diluted ore tonnes t - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m 1 313 2 704 3 474 4 201 4 241 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 48 940 Waste tonnes t 19 984 25 275 22 593 27 305 27 664 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 341 399 Total diluted ore tonnes t 1 636 16 758 48 934 72 812 89 558 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 131 558 Total carats cts 603 9 083 28 486 43 017 53 612 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 682 338 Ave tonnes per month 136 1 396 4 078 6 068 7 463 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Mining Cost per ore tonne US$/t 54 54 54 50 50 42 40 40 40 42 50 50 54 45Mining Operating cost US$ 87 796 899 184 2 625 704 3 622 846 4 456 067 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 50 516 630

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING CAPEXDTS 6 - CESS


SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 2 335 139 244 861 2 580 000SHAFT EQUIPING 14 190 000 5 689 000 2 470 679 22 349 679LEVEL INFRASTRUCTURE 00 Level 686 380 686 3801 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 4 719 170 1 350 000 0 0 0 0 0 0 0 0 0 0 0 6 069 170MINING EQUIPMENT 1 399 000 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 13 543 000TOTAL ZAR 28 957 062 14 621 734 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 62 969 269TOTAL US$ 2 825 079 1 426 511 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 6 143 343


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (BASE CASE)MINING OPEXDTS 6 - CESS

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Production rate "sanity check"Stoping

Strike 1 900 m (but model only 1.9km) SG Fissure 2.79 t/m3 LevelFissure width 0.45 m SG Waste 2.70 t/m3

SG ore 2.79 t/m3 SG diluted fissure (ave) 2.75 t/m3 Raise Stability pillar2 385 t/vm Swell factor 1.60 12.0 Mining direction

Deepening rate 30 mpa Interlevel spacing 40 m 33 55.6 40 71 564 tpa Stability pillar 5 m 66 Progressive face positions5 964 tpm Face angle 30 degrees

Stope working height 1.80 m 6 SIDE ELEVATIONStoping width 0.85 m Face length 66 Fissure grade 120 cpht Linear advance per month 12 m Month 1 M2 M3 M4 M5 30

Volume fissure per month 150 m3

Width Height Area Tons/m Tons fissure per face per month 419 t 20 15 12.5 12.0 12.0 Fissure drives 1.5 2.0 3.0 8.18 Tons waste per month 360 t LevelRock drives 2.0 2.0 4.0 10.80 Stope tons per month 779 t Crosscut Decreasing monthly face advance with increasing face lengthCrosscuts 2.0 2.0 4.0 10.80 Swell remaining at end of level #REF! tRaises 0.85 1.5 1.3 3.50 Vent Raiese 1.5 1.5 2.3 6.08 Mining recovery 95% Fissure

Travelling Ways 1.5 1.5 2.3 6.08 Fissure drive 6Dams, cubbies 2.0 2.0 4.0 10.80 CrosscutPasses 2.0 2.0 4.0 10.80 Rock driveDecline 2.5 2.5 6.3 16.88 10

PLAN VIEWCrosscut interval 10 m (production levels)

40 m (0L, top access) M1 M2 M3 M4 M5 M6 M7Crosscut length 6 m Face advance 20 15 12.5 12 12 12.0 12.0 W/shops, dams, cubbies, etc 20 m per End-of-month face length 23.1 40.4 54.8 66.0 66.0 66.0 66.0

500 m of strike Average face length 11.5 31.8 47.6 60.4 66.0 66.0 66.0Raise length 38 m Centares broken 115 238 298 334 334 334 334 T/way length 8 mT/way interval 40 m Labour rates TCTCDecline gradient 11 degrees Grade Lower Median Lower Width Height Area Tons/m $/mCrown pillar thickness 20 m, vertical quartile quartile Shaft 3 5 11 30 n/aTons fissure produced per m strike 64.94 tons per linear (strike) m A 7 618 8 390 9 086 Station 4 3 12 32 350 Shaft overwind 10 m, vertical BL 11 670 12 967 14 263 Station crosscut 2 3 5 14 350 Decline "overwind" 5 m, along decline BU 15 600 17 333 19 066 Orepass 2 2 4 11 220

CL 24 109 26 788 29 467 Pump station 4 3 12 32 350 Capital items See "Summary" sheet for annual totals CU 32 227 35 808 39 389 Rock drives 2 2 4 11 300

DL 49 807 55 341 60 875 Crosscuts 2 2 4 11 220 DU 66 579 73 976 81 374 Raises 1 2 2 5 220 EL 102 896 114 329 125 762 Boxholes 1 2 2 5 220

Level Depth, mbs0L, Top access 20 45kW fan 30 000R 1L, production 60 2L, production 100 3L, production 140 4L, production 180 5L, production 220 6L, production 260 7L, production 300 8L, production 340 9L, conveyor 360

Check Shaft bottom 370 Strike 1 900 mFissure width 0.45 m Decline to 0L 105 mDepth 300 m Decline to 1L 215 m additional (past 0L)SG ore 2.79 t/m3 Total decline length 319 mResource tons in situ 715 635 t, in situ 1L productionResource carats in situ 858 762 cts, in situ Access on 1L is 206 m from centre of strike

Allowances for mining Orepasses between levelsCrown pillar, subtract 20 m Drop raising 1 m per blastStability pillars, subtract 5 for each of 8 Assume 1 blast per day

ie 40 m Thus 30 m per monthMiing recovery, losses 95%Mineable tons (fissure only) 543 883 t Drop raising 2 000$ /m"Mineable" carats 652 659 ctScheduled carats 682 338 ct

ie 105% of "Mineable" carats

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Financial model Option A

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION A)INPUTS



STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION A)FINANCIAL MODELUS$

YEAR -3 YEAR -2 YEAR -1 YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$

MINING Surface MiningWaste t - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Ore Mined t 327 240 75 636 133 475 118 129 0 0 0 0 0 0 0 0 0 0 0 0 0Carats Recovered cts 120 528 27 469 48 475 44 583 0 0 0 0 0 0 0 0 0 0 0 0 0Underground MiningDecline Waste t - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Shaft Waste t 26 669 0 0 0 12 251 12 528 1 890 0 0 0 0 0 0 0 0 0 0Metres Developed m 43 987 0 0 0 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806Total Waste Mined t 307 490 0 0 0 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327Ore Mined t 1 116 014 0 0 0 0 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486Carats Recovered cts 676 612 0 0 0 0 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351Total MiningWaste t 26 669 0 0 0 12 251 12 528 1 890 0 0 0 0 0 0 0 0 0 0Ore Mined t 1 443 254 75 636 133 475 118 129 0 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486Carats Recovered cts 797 140 27 469 48 475 44 583 0 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351REVENUERevenue Per Carat $ 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270Project Revenue $000's 215 228 7 417 13 088 12 037 - 2 062 7 301 11 224 14 264 17 706 21 148 24 538 24 909 19 449 15 680 15 400 9 005TOTAL COSTS $000's 141 878 14 864 10 021 9 440 5 390 5 599 7 469 7 876 8 877 8 706 9 782 10 981 10 737 9 189 8 464 8 265 6 217Total Working Costs $000's 120 070 6 347 10 009 9 038 1 402 3 761 6 036 7 405 7 823 8 082 8 999 10 162 10 249 8 669 8 252 8 151 5 683Head Office $000's 960 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60Underground Mining (CESS Mining Only) $000's - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Surface Mining (including CESS U/G Mining) $000's 64 381 3 330 5 876 5 200 0 688 2 415 3 696 4 350 4 519 5 119 5 930 5 996 4 934 4 765 4 692 2 870Plant $000's 1 706 89 156 138 - 20 57 85 105 127 152 176 178 139 112 110 63Engineering $000's 13 156 605 1 068 945 387 552 673 764 828 899 983 1 063 1 063 937 850 845 696Security $000's 445 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28Manpower $000's 15 317 1 038 1 038 1 038 427 1 571 1 571 1 359 888 799 799 799 799 799 799 799 799Infrastructure $000's 4 433 159 159 159 228 228 228 228 269 326 389 451 456 356 287 283 228Logistics $000's 2 963 147 255 226 26 60 126 165 199 206 233 268 270 224 211 209 136Environmental $000's 1 015 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63Contingency $000's 15 693 828 1 306 1 179 183 491 815 956 1 034 1 054 1 174 1 325 1 337 1 131 1 076 1 063 741Cost Per Tonne Treated $/t 108 - - - - 293 134 108 89 74 69 68 68 73 86 86 106Total Capital Expenditure $000's 21 808 8 516 12 403 3 988 1 838 1 433 471 1 054 624 783 819 488 520 212 113 534Head Office $000's 10 10 - - - - - - - - - - - - - - -Underground Mining (CESS Mining Only) $000's - - - - - - - - - - - - - - - - -Surface Mining (including CESS U/G Mining) $000's 5 782 699 - - 1 933 1 258 790 165 222 168 311 235 - - - - -Plant $000's 3 214 3 214 - - - - - - - - - - - - - - -Engineering $000's 2 472 1 831 - - 641 - - - - - - - - - - - -Security $000's 213 213 - - - - - - - - - - - - - - -Infrastructure $000's 1 557 1 090 - - 467 - - - - - - - - - - - -Logistics $000's 360 252 - - 108 - - - - - - - - - - - -Environmental $000's 537 98 - - - - - - - - - - - - - - 439Major replacement $000's 4 798 - 10 350 319 319 456 244 694 375 370 477 424 452 185 98 25Contingency $000's 2 867 1 111 2 53 520 262 187 61 137 81 102 107 64 68 28 15 70Notional Profit (000's) (7 447) 3 067 2 597 (5 390) (3 537) (169) 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788



STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION A)MINING SUMMARY ***SURFACE SLOT 2: BENCH STOPING

MINING UNIT Y -3 Y -2 Y -1 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t - - - - - - - - - - - - - - - - - Fissure Mined per Pit t 13 465 13 465 13 465 - - - - Ore Mined per Pit t 44 492 44 492 44 492 - - - - - - - - - - - - - Number of Pits No 2 3 3 - - - - - - - - - - - - - Total Fissure Mined t 22 891 40 396 37 153 - - - - 100 440 Total Ore Mined t 75 636 133 475 118 129 - - - - - - - - - - - - - 327 240 Carats Recovered cts 27 469 48 475 44 583 - - - - - - - - - - - - - 120 528 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - - - - Shaft waste tonnes t - - - 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - - - - 1L diluted ore tonnes t - - - - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - - - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m - - - 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t - - - 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - - - - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Total carats cts - - - - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - - - - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t - - - 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 Total diluted ore tonnes t 75 636 133 475 118 129 - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 Total carats cts 27 469 48 475 44 583 - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 Underground Mining Cost per ore tonne US$/t - - - 54 54 54 54 50 42 40 40 40 42 50 50 54 58Surface Mining Costs US$/t 42 42 42 - - - - - - - - - - - - - Surface Materials Handling US$/t 2 2 2 - - - - - - - - - - - - - Mining Operating cost US$ 3 329 741 5 876 013 5 200 451 - 688 473 2 414 994 3 696 280 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 64 381 217

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION A)MINING CAPEXSURFACE SLOT 2: BENCH STOPING

YEAR -3 YEAR -2 YEAR -1 YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13 TOTALZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR

SURFACE MININGUnderground Infrastructure 0 0Vertical Access 1 627 316 1 627 316Mining Equipment 2 840 175 2 840 175Surface Facilities 2 693 436 2 693 436SURFACE MINING SUB TOTAL 7 160 927 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 160 927SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 0 0 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 0 0 0 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 7 160 927 0 0 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 59 260 646TOTAL US$ 698 627 0 0 1 933 402 1 257 744 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 5 781 526


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION A)MINING OPEXSURFACE SLOT 2: BENCH STOPING


MINING OPEX UNIT 2002 2008 2012 2014 �


Average RSA CPI 6%

PLANT OPEX UNIT Y -3 Y -2 Y -1 TOTALSurface tonnes treated t 75 636 133 475 118 129 327 240Unit cost per tonne treated ZAR/t 12 12 12 12Surface plant costs ZAR 907 629 1 601 699 1 417 552 3 926 880CESS plant costs ZAR 0 0 0 0


ENGINEERING OPEX UNIT Y -3 Y -2 Y -1 TOTALSurface tonnes treated t 75 636 133 475 118 129 327 240Engineering costs per tonne treated US$/t 8 8 8 8Surface engineering costs US$ 605 086 1 067 799 945 035 2 617 920CESS engineering costs US$ 0 0 0 0

TOTAL ENGINEERING COSTS US$ 605 086 1 067 799 945 035 2 617 920

MANPOWER OPEX UNIT Y -3 Y -2 Y -1 TOTALCESS manpower costs US$ 0 0 0 0Additional surface manpower costs US$ 1 038 000 1 038 000 1 038 000 3 114 000


LOGISTICS OPEX UNIT Y -3 Y -2 Y -1 TOTAL3.5% of Opex US$ 147 372 255 057 226 487 628 916

OPEX CONTINGENCY UNIT Y -3 Y -2 Y -1 TOTAL15% of Opex US$ 827 914 1 305 571 1 178 842 3 312 327





Financial model Option B

STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION B)INPUTS



STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION B)FINANCIAL MODELUS$

YEAR -2 YEAR -1 YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$ US$

MINING Surface MiningWaste t - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Ore Mined t 327 240 75 636 133 475 118 129 0 0 0 0 0 0 0 0 0 0 0 0Carats Recovered cts 120 528 27 469 48 475 44 583 0 0 0 0 0 0 0 0 0 0 0 0Underground MiningDecline Waste t - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Shaft Waste t 26 669 0 0 12 251 12 528 1 890 0 0 0 0 0 0 0 0 0 0Metres Developed m 43 987 0 0 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806Total Waste Mined t 307 490 0 0 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327Ore Mined t 1 116 014 0 0 0 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486Carats Recovered cts 676 612 0 0 0 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351Total MiningWaste t 26 669 0 0 12 251 12 528 1 890 0 0 0 0 0 0 0 0 0 0Ore Mined t 1 443 254 75 636 133 475 118 129 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486Carats Recovered cts 797 140 27 469 48 475 44 583 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351REVENUERevenue Per Carat $ 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270Project Revenue $000's 215 228 7 417 13 088 12 037 2 062 7 301 11 224 14 264 17 706 21 148 24 538 24 909 19 449 15 680 15 400 9 005TOTAL COSTS $000's 140 222 14 864 10 021 13 143 5 631 7 469 7 876 8 877 8 706 9 782 10 981 10 737 9 189 8 464 8 265 6 217Total Working Costs $000's 118 781 6 347 10 009 9 119 3 793 6 036 7 405 7 823 8 082 8 999 10 162 10 249 8 669 8 252 8 151 5 683Head Office $000's 900 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60Underground Mining (CESS Mining Only) $000's - 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Surface Mining (including CESS U/G Mining) $000's 64 381 3 330 5 876 5 200 688 2 415 3 696 4 350 4 519 5 119 5 930 5 996 4 934 4 765 4 692 2 870Plant $000's 1 706 89 156 138 20 57 85 105 127 152 176 178 139 112 110 63Engineering $000's 12 769 605 1 068 945 552 673 764 828 899 983 1 063 1 063 937 850 845 696Security $000's 417 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28Manpower $000's 14 890 1 038 1 038 1 038 1 571 1 571 1 359 888 799 799 799 799 799 799 799 799Infrastructure $000's 4 274 159 159 228 228 228 228 269 326 389 451 456 356 287 283 228Logistics $000's 2 940 147 255 229 60 126 165 199 206 233 268 270 224 211 209 136Environmental $000's 951 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63Contingency $000's 15 552 828 1 306 1 189 522 815 956 1 034 1 054 1 174 1 325 1 337 1 131 1 076 1 063 741Cost Per Tonne Treated $/t 106 - - - 296 134 108 89 74 69 68 68 73 86 86 106Total Capital Expenditure $000's 21 442 8 516 12 4 024 1 838 1 433 471 1 054 624 783 819 488 520 212 113 534Head Office $000's 10 10 - - - - - - - - - - - - - -Underground Mining (CESS Mining Only) $000's - - - - - - - - - - - - - - - -Surface Mining (including CESS U/G Mining) $000's 5 782 699 0 1 933 1 258 790 165 222 168 311 235 0 0 0 0 0Plant $000's 3 214 3 214 - - - - - - - - - - - - - -Engineering $000's 2 472 1 831 - 641 - - - - - - - - - - - -Security $000's 213 213 - - - - - - - - - - - - - -Infrastructure $000's 1 557 1 090 - 467 - - - - - - - - - - - -Logistics $000's 360 252 - 108 - - - - - - - - - - - -Environmental $000's 537 98 - - - - - - - - - - - - - 439Major replacement $000's 4 479 - 10 350 319 456 244 694 375 370 477 424 452 185 98 25Contingency $000's 2 819 1 111 2 525 262 187 61 137 81 102 107 64 68 28 15 70Notional Profit (000's) (7 447) 3 067 (1 106) (3 569) (169) 3 348 5 386 9 000 11 366 13 557 14 171 10 260 7 215 7 136 2 788



STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION B)MINING SUMMARY ***SURFACE SLOT 2: BENCH STOPING

MINING UNIT Y -2 Y -1 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 TotalSurface MiningWaste t - - - - - - - - - - - - - - - - Fissure Mined per Pit t 13 465 13 465 13 465 - - - Ore Mined per Pit t 44 492 44 492 44 492 - - - - - - - - - - - - Number of Pits No 2 3 3 - - - - - - - - - - - - Total Fissure Mined t 22 891 40 396 37 153 - - - 100 440 Total Ore Mined t 75 636 133 475 118 129 - - - - - - - - - - - - 327 240 Carats Recovered cts 27 469 48 475 44 583 - - - - - - - - - - - - 120 528 Underground MiningDecline waste tonnes t - - - - - - - - - - - - - - - - Shaft waste tonnes t - - 12 251 12 528 1 890 - - - - - - - - - - 26 669 0L bulk sample tonnes t - - - - - - - - - - - - - - - - 0L bulk sample carats cts - - - - - - - - - - - - - - - - 1L diluted ore tonnes t - - - 12 831 21 058 21 058 21 058 21 058 21 058 20 534 5 275 - - - - 143 928 2L diluted ore tonnes t - - - - 17 239 20 060 21 058 21 058 21 058 21 058 20 141 2 285 - - - 143 956 3L diluted ore tonnes t - - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - - 143 928 4L diluted ore tonnes t - - - - - 6 710 21 058 21 058 21 058 21 058 21 058 21 058 10 872 - - 143 928 5L diluted ore tonnes t - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 21 712 13 727 - 143 928 6L diluted ore tonnes t - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 35 439 - 143 928 7L diluted ore tonnes t - - - - - - - - 3 200 21 058 21 058 21 058 21 058 24 068 32 429 143 928 8L diluted ore tonnes t - - - - - - - - - 3 200 21 058 21 058 21 058 21 058 21 058 108 489 Total metres developed m - - 550 1 554 2 316 2 983 3 577 4 404 5 220 5 847 5 385 4 156 3 547 3 642 806 43 987 Waste tonnes t - - 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 307 490 Total diluted ore tonnes t - - - 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 1 116 014 Total carats cts - - - 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 676 612 Ave tonnes per month - - - 1 069 3 751 5 740 7 286 9 041 10 796 12 507 12 647 9 870 7 980 7 858 4 457 Total MiningTotal waste t - - 12 251 17 346 15 771 19 930 23 613 29 155 34 590 38 734 35 798 27 592 23 464 23 920 5 327 Total diluted ore tonnes t 75 636 133 475 118 129 12 831 45 007 68 885 87 431 108 489 129 546 150 081 151 762 118 446 95 757 94 292 53 486 Total carats cts 27 469 48 475 44 583 7 637 27 040 41 571 52 829 65 578 78 326 90 882 92 255 72 033 58 073 57 038 33 351 Underground Mining Cost per ore tonne US$/t - - 54 54 54 54 50 42 40 40 40 42 50 50 54 58Surface Mining Costs US$/t 42 42 42 - - - - - - - - - - - - Surface Materials Handling US$/t 2 2 2 - - - - - - - - - - - - Mining Operating cost US$ 3 329 741 5 876 013 5 200 451 688 473 2 414 994 3 696 280 4 350 233 4 519 485 5 118 665 5 930 012 5 996 468 4 934 276 4 764 503 4 691 623 2 870 000 64 381 217

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STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION B)MINING CAPEXSURFACE SLOT 2: BENCH STOPING

YEAR -2 YEAR -1 YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 YEAR 10 YEAR 11 YEAR 12 YEAR 13 TOTALZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR ZAR

SURFACE MININGUnderground Infrastructure 0 0Vertical Access 1 627 316 1 627 316Mining Equipment 2 840 175 2 840 175Surface Facilities 2 693 436 2 693 436SURFACE MINING SUB TOTAL 7 160 927 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 160 927SHAFT SINKING 5 627 373 5 754 493 868 135 12 250 000DECLINE DEVELOPMENT 0 0 0 0SHAFT EQUIPING 14 190 000 5 554 000 2 470 679 22 214 679LEVEL INFRASTRUCTURE 00 Level 0 01 Level 686 380 686 3802 Level 686 380 686 3803 Level 686 380 686 3804 Level 686 380 686 3805 Level 686 380 686 3806 Level 686 380 686 3807 Level 686 380 686 3808 Level 686 380 686 380DECLINE EQUIPING 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0MINING EQUIPMENT 0 0 0 897 000 3 391 000 1 004 000 1 592 000 1 036 000 2 502 000 1 722 000 0 0 0 0 0 12 144 000UNDERGROUND MINING SUB TOTAL 0 0 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 52 099 719TOTAL ZAR 7 160 927 0 19 817 373 12 891 873 8 102 574 1 690 380 2 278 380 1 722 380 3 188 380 2 408 380 0 0 0 0 0 59 260 646TOTAL US$ 698 627 0 1 933 402 1 257 744 790 495 164 915 222 281 168 037 311 061 234 964 0 0 0 0 0 5 781 526


STELLAR DIAMONDSTONGO - MINING OPTIONS DESKTOP STUDY (OPTION B)MINING OPEXSURFACE SLOT 2: BENCH STOPING


MINING OPEX UNIT 2002 2008 2012 2014 �


Average RSA CPI 6%

PLANT OPEX UNIT Y -2 Y -1 Y1 TOTALSurface tonnes treated t 75 636 133 475 118 129 327 240Unit cost per tonne treated ZAR/t 12 12 12 12Surface plant costs ZAR 907 629 1 601 699 1 417 552 3 926 880CESS plant costs ZAR 0 0 0 0


ENGINEERING OPEX UNIT Y -2 Y -1 Y1 TOTALSurface tonnes treated t 75 636 133 475 118 129 327 240Engineering costs per tonne treated US$/t 8 8 8 8Surface engineering costs US$ 605 086 1 067 799 945 035 2 617 920CESS engineering costs US$ 0 0 0 0

TOTAL ENGINEERING COSTS US$ 605 086 1 067 799 945 035 2 617 920

MANPOWER OPEX UNIT Y -2 Y -1 Y1 TOTALCESS manpower costs US$ 0 0 0 0Additional surface manpower costs US$ 1 038 000 1 038 000 1 038 000 3 114 000


LOGISTICS OPEX UNIT Y -2 Y -1 Y1 TOTAL3.5% of Opex US$ 147 372 255 057 228 878 631 307

OPEX CONTINGENCY UNIT Y -2 Y -1 Y1 TOTAL15% of Opex US$ 827 914 1 305 571 1 189 451 3 322 936

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TONGO MINE MINING OPTIONS DESKTOP STUDY - …stellar-diamonds.com/wp-content/uploads/2014/12/Tongo...TONGO MINE MINING OPTIONS DESKTOP STUDY FOR December 2014 Confidentiality Notice