The GemGuide Value Factors of Colored Gemstones May/June 2016 u 1

In this comprehensive article, the author discussesthe value factors of colored gems in five parts. Partsone and two appeared in Gem Market News, January/February 2016, Volume 35, Issue 1. Parts three andfour appeared in Gem Market News, March/April2016, Volume 35, Issue 2. What follows is the fifthand final part.

Part 5: Craftsmanship and SummaryPart 1 discussed the major value factors that affect theprice of a colored gemstone which included cut quality.Part 2 defined aspects of cutting styles to establishsome common language, with a focus on basic facetingstyles, and a short discussion on cabochons and beads.Part 3 spoke about dark patterns in a gem and whatcauses them. Part 4 explored many of the factors usedin the trade (rightly or wrongly) to assess relative valueas well as explained some of the additional choices cut-ters make and why. Part 5 will discuss craftsmanship’sbearing on cut quality.

Wireframes or depictions of facet arrangements (suchas Fig. 5-07) are from scans of real gems so as to illus-trate certain aspects of gem cutting. Face-up patterns(such as Fig. 5-03, right) were made using the programDiamCalc; adjustments were made to the refractiveindex to represent the gem material being demonstrated.DiamCalc cannot show double refraction.

CraftsmanshipCraftsmanship is a broad term that denotes how muchattention to detail the cutter gave to the finished gem.Most colored gemstones are cut in a variety of fancyshapes with many facet variations. Because of that, someaspects are less critical than others. Minor deviations ofcraftsmanship aren’t as critical as achieving the optimalcolor. However, very careful attention to detail isrewarded by being able to demand a higher price. As thegeneral value of the type of gem goes up, this becomestruer. A very well-cut richly hued citrine will not get as

much added benefit as a tourmaline with very exception-al color. Yet with very rare and expensive gems, thisbecomes less true, e.g., a very well-cut and fine-coloredsapphire will only benefit slightly from exceptional cut-ting. There are a number of elements that fold into crafts-manship which significantly impact value.

• Outline. The outline, or shape, of the stone shouldbe graceful and pleasing, and symmetrical (whenappropriate) (see Fig. 5-01). While all of these arepear shaped, none could be considered an idealizedpear shape. TRADEOFF: A finished gem of excep-tional cutting, color, or rarity can get away with aless pleasing shape provided it is still symmetrical(see Fig. 5-01, row 1). The cutter chose to recoversignificant weight from the rough due to what theyfelt was an important gem. The value per carat maybe less for that same stone if the outline lacks sym-metry (see Fig. 5-01, row 2), but the weight savedmay make it a gem that sells for more than one ofaverage color or size.

Gem Market News Feature

Value Factors, Design, and Cut Quality ofColored Gemstones (Non-Diamond)

Al Gilbertson, GG (GIA), CG (AGS)

Fig. 5-01. Illustration by Al Gilbertson, © GIA.

2 u May/June 2016 Value Factors of Colored Gemstones The GemGuide

• Table. The tableshould be centered,parallel to the girdle,and follow the gen-eral shape of thegem. A rectangulartable on an oval gemlooks out of place( see F ig . 5 -02 ) .Additionally there isusually an optimaltable size for the bestappearance for anyfacet arrangement,and the relative sizewill vary dependingupon a number offactors. Figure 5-03shows first the tablesize and facet arrangement, followed by imagesof the gems face-up, and lastly the gems tilted 15degrees, demonstrating that there is more win-dowing when tilted for gems with a large table ofthis facet arrangement. TRADEOFF: A cutterchose to cut the gem with a large table rather thancut several smaller gems. In extremely dark gems,a large table with shallow proportions can bepreferable to a gem that is extremely dark, since itlightens the color to a range that sells for more.

Very small tables are generally less desirable(see Fig. 5-03), and surprisingly, do not minimizewindowing. The greater crown height retains moreweight creating the perception that the gem is top-heavy and pointed.

• Shoulders. Shoulders on hearts, ovals, andpears (see Fig. 5-01) that look pinched are lesspleasing (see Fig. 5-01, row 1, fourth pearshape). Broad shoulders are acceptable if theoverall outline is still pleasing.

• Culet or Keel Line. The culet or keel line of thebottom of the gem needs to be centered (see Fig. 5-04). The more visibly off-center, the more it affectsthe perception of how well the gem was cut.

• General Symmetry. Looking at the gem face-up,mentally divide it into halves or quarters (fifths ifit is a pentagon, etc.) and look at how each seg-ment mirrors the others. If there is an impressionof a significant deficiency, this will also affectthe perception of the cut quality, and ultimatelythe gem’s value.

• Girdle Thickness and Unevenness. Girdlethickness rarely affects a gem’s face-up appear-ance. Extremely thin girdles should be avoidedas they are very easily chipped. While cornersand points (tips) are vulnerable to chipping,slightly thicker girdles at these spots are accept-able to help mitigate their vulnerability.Extremely thick girdles are difficult to set and

Fig. 5-03. Illustration by Al Gilbertson, © GIA.Fig. 5-02. Illustration by AlGilbertson, © GIA.

Fig. 5-04. Spinel,euclase, iolite. Photosby Robert Weldon, ©GIA.

The GemGuide Value Factors of Colored Gemstones May/June 2016 u 3

obviously add unnecessary weight. Extremeunevenness can be an important intentional partof a designer cut where certain parts of thedesign require a thicker portion of the girdle(e.g. corners on cushions) (see Fig. 5-05) anddon’t detract from the value as much when it isrequired for the cutting style. Other types ofextreme unevenness or waviness also lower theperception of the gem’s cut quality and ulti-mately its value.

• Girdles with Sharp Edges. Nathan Renfro(Analytical Manager, Identification at GIA,Carlsbad) points out that some cutters round thegirdle edges so that they are less likely to chipwhen being set. This means that the girdle edgemay not come to a sharp edge where the girdlemeets the crown or pavilion and that the girdleitself may not be flat.

• Polish. The late Stephen Kotlowski (Uniquely KCustom Gems) noted that all of the facets shouldlook like they are highly polished with a mirror-like quality, and this polish quality should beexamined under magnification. Poorer polishmeans less value and vice versa.

• Alignment of Crown and Pavilion.With certainfacet arrangements (e.g. step cuts, designer cuts),better crown and pavilion alignment will help setthe quality of cutting to a higher level. This align-ment is fairly unimportant in many standard oval,pear, and cushion shaped commercial-cut qualitygems unless it makes the girdle extremelyuneven. In hearts, this alignment can be seen inangular or mismatched lobes, and shallow ordeep or awkward clefts (see Fig. 5-06). Oftenthese deficiencies can be slightly masked by thedesign of the jewelry.

• Facet Meets. With designer cuts (see Fig. 5-07) it is more important and fairly expectedthat the facets should meet in sharp points witheach other, according to Stephen Kotlowski.Some designs will purposely have portionswithout standard meets, so be careful not to beoverly critical (see circled areas on the trianglein Fig. 5-07). Outline, facet symmetry, and pol-ish are more important than the exactness ofthe facet meets.

• Misshapen Facets.With designer cuts it is fairlyexpected that the facets should mirror each other.If the deviation is obvious to the unaided eyewhen the gem is viewed face-up, it can be dis-tracting and lessen the overall value of thedesigner cut. Wayne Emery (The Gemcutter)says, “In a designer or precision cut, there is noexcuse for any misshapen facets, not even slight-ly. It's too easy to be very precise; anything lessis poor workmanship.”

Fig. 5-05. Illustration by Al Gilbertson, © GIA.

Fig. 5-06. Illustration by Al Gilbertson, © GIA. Brazilianite, spinel. Photos by Robert Weldon, © GIA.

4 u May/June 2016 Value Factors of Colored Gemstones The GemGuide

• Rounded Facet Junctions. Ideally, adjoiningfacets should have sharp junctions. However it isnot uncommon to see slightly rounded facet junc-tions in commercial grade cutting. Unless thisslight rounding is eye-visible, it seldom detractsfrom the value of the gem, but it should. The dif-ference between stones with sharp flat facet junc-tions and those with very slightly rounded facetjunctions is notable. The flat facets and sharp edgesadd crispness to the appearance that cannot beachieved otherwise. The extra time needed to addthis care when cutting justifies a significant differ-ence in cost for a designer gem.

• Proportions. Proportions affect the face-upappearance of the gem in general, so calling outproportions any more than this article already has

is unnecessary (see Parts 3 and 4, GemMarket News March/April 2016).

• Bulge. Bulginess in the pavilion orcrown sacrifices the face-up beauty of agem while adding significant excessweight (even up to 35% and more).Often the jeweler pays less per carat forthe less attractive deep bulgy gem.

Re-cutting IssuesIt is not unusual for jewelers to want tore-cut a damaged or poorly cut gem.Re-cutting requires determining theadded expense versus the recoveredweight to see if it is worth the effort(don’t be surprised at substantialweight loss). Not all cutters have thesame philosophy about how a gemshould look when it is re-cut. Will theyre-polish an older style step-cut cush-ion without changing the angles sub-stantially, resulting in that older classicappearance? Or, do they want to use amodern cutting style and will the result-

ing face-up appearance match a consumer’s expecta-tions? Get recommendations from others who have usedtheir services, ask what they deem appropriate for thegem, and view examples of their work.

Cutters agree that the total number of facets is relativeto the finished size of the gem. Figure 5-08 shows threevery different facet arrangements for a round gem. Thefirst, with only 17 facets, is best utilized on small gems,generally under about 3 mm. More facets than that onsuch small gems will start to blur the effect of the facetingand be less interesting, especially if the material is strong-ly doubly refractive. The second example with 57 facets isgreat for sizes from about 4 to 11 mm. This facet patternwill be less interesting or dynamic on larger sizes. Gemslarger than 12 mm really need more facets, such as thethird diagram with 113 facets. Note that emerald cutsdon’t suffer when cut in all of these size variations.

Fig. 5-07. Illustration by Al Gilbertson, © GIA. Scheelite, peridot, phosgenite. Photosby Robert Weldon, © GIA.

Fig. 5-08. Illustration by Al Gilbertson, © GIA.

The GemGuide Value Factors of Colored Gemstones May/June 2016 u 5

Wayne Emery points out that the relative size of thefacets, especially on the crown, is important to a pleas-ing design. There are some designs that split the star orupper girdle facets into several small facets, while leav-ing the crown mains large. At first glance, this type ofcutting will result in a disappointment. Crown facetsneed to be evenly sized not only to keep the color moreevenly spread, but to create a better face-up appeal.

Craftsmanship Evaluation of “Fantasy Cuts andArtistic Cutting” Noted gemstone artists DalanHargrave (of Gemstarz) andMark Gronlund (of G3Gems) were kind enough toshare some critical insightsfor evaluating the craftsman-ship of concave faceting. V-grooves and concave dish-shaped grooves or facets aretwo types of applications tocolored gems. There arethree ways to evaluate theseapplied styles of cutting:

• Finish. Using a loupe,look at the inside ofthe facets and groovesor concave areas. Theedges of where theconcavities meet thefacets should be sharp-edged and free fromchipping (see Figs. 5-11b and 5-11c). Thesurfaces should allhave a very high, even

Fig. 5-10a. Cubic zirconia topand side view cut by D.K. Kim.Photo by Orasa Weldon, © GIA.

Fig. 5-10b. Cubic zirconia bot-tom view cut by D.K. Kim. Photoby Robison McMurtry. © GIA.

Fig. 5-10c. Cubic zirconia closeup side cut by D.K. Kim. Photoby Robison McMurtry. © GIA.

Fig. 5-10d. Cubic zirconia close up top cut byD.K. Kim. Photo by Jonathon Muyal. © GIA.

Fig. 5-09a. Blue topaz top and side view. Photo by Orasa Weldon, © GIA.

Fig. 5-09b. Blue topaz ends of grooves. Photo by Robison McMurtry. © GIA.

Fig. 5-09c. Blue topaz unpolished grooves. Photo by Jonathon Muyal. © GIA.

6 u May/June 2016 Value Factors of Colored Gemstones The GemGuide

polish. Mass-produced work or lesser quality workwill often have chipped edges and grooves fromthe cutting tools that haven’t been polished out (seeFig. 5-09c). Sometimes there may be pock-marksbecause the polishing did not remove the earliergrinding done with coarser grits (see Fig. 5-09cand 5-10d). Distorted polished surfaces are com-mon with lower quality goods (see Fig. 5-10d).

• Central Brilliance. Since the purpose of thesereflections is to enhance the brilliance and visualinterest of the gem, concave faceting works very eas-ily with round gems, as it brings the visual interest tothe center. For odd shaped gems, this centrality offocus is harder to achieve, but can still be used toaccent a portion of the gem (see Fig. 5-12). Thesereflections are playing with optics or using light in anew way in a particular gem material to create strongcontrast patterns. The effect should enhance the“central brilliance” of the gem and make interestingpatterns. The application of a few grooves on thepavilion or at the edge of the gem is easily done andmass-produced (see Fig. 5-09a), while applying themin a way that provides a visually vibrant pattern withcentral brilliance takes more artistic ability and work.

Even the freeform sunstonefrom Figure 5-12 has opti-cal dishes placed in a man-ner that points the eye tothe central green area.Without these dishes, thesunstone would be lessvisually interesting. Centralbrilliance can also be sym-metrical, so that if youwere to fold the gem inhalf, one side mirrors theother (called line-symme-try). The long rectangulartourmaline in Figure 5-12has a line-symmetry typeof brilliance. Central bril-liance is not seen in all fan-tasy items, but when pres-ent enhances the face-upappearance of the gem.

• Symmetry of GroovePlacement. Grooves andconcavities that are sym-metrical or laid out in a

well-developed pattern not only enhance the cen-tral brilliance, but show a consistency even undermagnification. The sunstone of Figure 5-12 doesnot have symmetrically placed optical dishes,whereas the concave facets in the tourmaline in thesame figure have a high level of symmetry. Addedsymmetry adds more value.

Fig. 5-12.Sunstone and tour-maline cut by JohnDyer. Photo courtesyof John Dyer & Co.

Fig. 5-11d. Ametrine close up top cut by DalanHargrave. Photo by Jonathon Muyal. © GIA.

Fig. 5-11c. Ametrine close up side cut by DalanHargrave. Photo by Jonathon Muyal. © GIA.

Fig. 5-11b. Ametrine close up center cut byDalan Hargrave. Photo by Jonathon Muyal. © GIA.

Fig. 5-11a. Ametrine top and side view cut byDalan Hargrave. Photo by Orasa Weldon, © GIA.

The GemGuide Value Factors of Colored Gemstones May/June 2016 u 7

Four Examples of Fantasy Cutting

• The oval blue topaz (see Fig. 5-09a) has a seriesof cross-hatch style grooves on one side of thepavilion. When observed face-up, the groovesreflect to the other side and fill the gem with theeffect. The ends of the grooves are uneven andirregular (see Fig. 5-09b). There is small chipping

and abrading at some of the places where the crosshatching occurs (see Fig. 5-09c) and at the end ofsome of the grooves. The bottoms of the valleys ofall of the grooves are well polished, but the groovewalls have scoring from the original grinding thathas not been polished out (see Fig. 5-09c). This isan indication of lesser cutting quality and/or mass-manufacturing.

• The star-shaped CZ (see Fig. 5-10a) is groovedat the girdle to create a star-styled outline. Whenlooking at the gem face-down, some of thegrooves are not evenly spaced (see Fig. 5-10b),are not perpendicular to the table, and tilt at anangle (see Fig. 5-10c). The walls of the grooveshave scoring from the original grinding of thegrooves that has not been completely polished(see Fig. 5-10d). This is an indication of lessercutting quality and/or mass-manufacturing. Inthis case, it is a poorly executed knock-off of apatented design by Wobito.

• The drop-shaped ametrine (cut by DalanHargrave—see Fig. 5-11a) is good example of con-cave faceting that uses v-shaped grooves on theback of the gem (see Figs. 5-11b and 5-11c) foroptical effect. A closer look from the back of thegem shows that the grooves are all well-polishedand the ends of the grooves are chip and abrasion-free. This is typical of fantasy gems of high quali-ty. Dalan employs a technique that curves thegrooves seen in the top of the face-up image ofFigure 5-11a. Note also the symmetry of thegroove placement. The grooves used for the cross-hatched pattern create bright lines of contrast,emphasizing a central brilliance in that portion ofthe gem. The curved grooves also create stronglines of contrast, adding a line-symmetry to the topportion of this gem.

• Not all concave faceting uses grooves to createcontrast. A more careful examination of ChrisWolfsberg’s design for an ametrine (see Fig. 5-13a)demonstrates how the use of more gently curvedconcave facets helps create the unique outline ofthe gem. Another example of very fine craftsman-ship, Wolfsberg uses evenly polished, concavecurved or dished facets that are very carefullymatched to mirror each other (see Fig. 5-13b).There are no unpolished, abraded, or chipped areas(see Figs. 5-13c and 5-13d).

Fig. 5-13a.Illustration by AlGilbertson, © GIA.

Fig. 5-13b. Ametrine top viewcut by ChrisWolfsberg. Photoby Orasa Weldon, © GIA.

Fig. 5-13c. Ametrine close upback cut by ChrisWolfsberg. Photoby RobisonMcMurtry. © GIA.

Fig. 5-13d. Ametrine close upside cut by ChrisWolfsberg. Photoby RobisonMcMurtry. © GIA.

8 u May/June 2016 Value Factors of Colored Gemstones The GemGuide

SummaryFaceting is a series of compromises. The cutter com-pares various tradeoffs to make decisions about cut-ting the final gem. Most importantly, the cutter needsto achieve the best face-up color possible from thatgem. The shape (outline) needs to be aestheticallypleasing and desirable, while the quality of the cuttingshould provide an attractive contrast pattern thatenhances the color.

Many jewelers and gem dealers haven’t taken the timeto understand the difference between good gem cuttingand great gem cutting. With a little effort, it is alwayspossible to detect the hand of a dedicated artisan in theircreation. We often sacrifice values of real craftsmanshipat the altar of “good enough.” In a world that places apremium on low price, disposable goods, and speed ofgetting things done, craftsmanship suffers. Even thoughwe are able to quickly realize the quality of somethingthat has been expertly cut, many often choose the cheapand average gem instead. Diamonds have gone through abit of commoditization over the years, and much of thepublic and most of the trade is keenly aware of priceranges for certain goods. High quality cutting in dia-monds is now appreciated. Prices for colored gems arevery blind to the public and even many jewelers, so qual-ity can be sacrificed and sellers can purport fictitious“good deals.” It’s time to set good enough aside.

Expert craftsmanship comes from creativity, and apassion and attention to detail that improves over thelength of an artisan’s career as they seek to do better. Theartisan grows as they pay more attention to the smalldetails. Too often the jewelry trade treats highly skilledprofessionals as something they don’t think they want tosell, since they think that the work is too expensive. Bylearning the difference and becoming passionate about

quality in the goods you sell, you pass on to the con-sumer an attitude that says good enough is not goodenough. You pass on a care for the detail and an abilityto recognize and appreciate quality.

In a world that seems to want to treat all of us thesame, people struggle to point out their own uniqueness.Some do it by their clothing or lifestyle, others by whatthey drive. Why not demonstrate their uniqueness by thequality of the fine gems they wear? Handling and sellingquality craftsmanship is at the heart of getting out of therut of good enough. It’s also key to earning the respectof clients and customers, and ultimately creating friends(your clients) who appreciate fine quality. u

Thanks to Wayne Emery (The Gemcutter), BrookeGoedert (Sr. Research Data Specialist, GIA Carlsbad),Josh Hall (Vice President of Pala International, Inc.), Dalan Hargrave (Gemstarz), Richard Hughes (LotusGemology), Stephen Kotlowski (Uniquely K CustomGems), Andy Lucas (Manager, Field Gemology-Education, Content Strategy-Gemology, GIA,Carlsbad), and Nathan Renfro (Analytical Manager,Identification at GIA, Carlsbad) for reviewing this article and providing valuable input.

About the Author: Al Gilbertson is the ProjectManager, Cut Research at the Gemological Institute of America Laboratory Carlsbad. He made significantcontributions while functioning on the American GemSociety (AGS) Cut Task Force, when his patent wasacquired by AGS and is the foundation of their ASETtechnology for cut grading. Hired by GIA in 2000, hebecame part of GIA’s team that created the current cutgrading system for round brilliant diamonds. Al is alsothe author of American Cut—The First 100 Years.

Gemworld International, Inc., 2640 Patriot Blvd, Suite 240, Glenview, IL 60026-8075, www.gemguide.com© 2016 Gemworld International, Inc. All rights reserved.

All articles and photographs that appear are copyrighted by the author, the contributing person or company, or Gemworld International, Inc. and my not be reproduced in any printed or electronic format, posted on the internet, or distributed in any way without written permission. Address requests to the editor-in-chief.

The opinions expressed in this publication are the opinions of the individual authors only and should not necessarily be considered to be the opinions of the staff of Gemworld International, Inc.as a whole. Any website listings that appear in articles are for informational purposes only and should not be considered an endorsement of that company.