Book Reviews: Kapur on J. B. Tavernier, Hughes on Ruby/Sapphire, Yavvorskky on Garnet

Jean Baptiste Tavernier, A Life:  KAPURIMAGE

Harish Kapur’s reasonably well written short biography of Jean Baptiste Tavernier, the 17th Century gem dealer who  the Hope Diamond has quite a bit to recommend it.  He covers the important parts of Tavernier’s life, travels and writing.  I am particularly taken by his ability to extract from the minutia of Tavernier’s long life, some of the more salient points.    

Unfortunately, the narrative is marred by a number of factual errors.  The most egregious, perhaps resulting from an injudicious use of MSWord’s find/replace shortcut the word “diamond” in the last two thirds of the manuscript has been replaced by “pearl.”  For the uninformed reader, this results in a number of misstatements about Tavernier’s objectives and focus as well as a several absurd statements concerning the “mining” of pearls and the “pearl mines” of India.   A photo of a drawing from Tavernier’s Six Voyages, of a diamond that became known as The Mirror of Portugal is ludicrisly mis-labeled “The Sara Pearl.”

The author also somehow misquotes Tavernier’s assertion that he traveled 60,000 leagues which becomes 600,000 leagues.  At three miles to the league that leads to the ridiculous assertion that Tavernier traveled not 180,000 (an amazing accomplishment in the 17th Century) but 1.8 million miles, which would have required 72 circumnavigations of the earth.  

Kapur also quotes an unfortunate statement made by New York Times reporter Guy Trebay (1/6/10) suggesting that Tavernier may have been involved in the acquisition of the Wittelesbach-Graff Diamond.  Though the diamond is first mentioned in 1677, while Tavernier was STILL in India completing his sixth and final voyage, there is absolutely no documentation supporting this theory.  Tavernier did mention several gems he successfully acquired and though he does not actually mention the 116 carat Tavernier Blue, the gem that eventually became the Hope, he did include a drawing of it in his book, The Six Voyages.

On the plus side, the book includes several appendices containing documents never before available to the English speaking reader and his research raises a number of intriguing theories regarding Tavernier’s motivations, travels, life and death.  Unfortunately, his sloppy copy editing may lead frustrated readers to disregard most of the  author’s conclusions.

Last, and certainly not least, in the bibliography, which includes my partly fictionalized biography of Tavernier, The French Blue, the author confuses me with someone named Robert.

 


Ruby & Sapphire, A Collector's Guide

In this general reference which can be looked upon as an update and supplement to his classic Ruby and Sapphire, Hughes, as usual, offers a uniquely personal insight into the world of corundum.

 

HughesUpdate His ability to blendup to date information with arcane references is a delight.  This volume together with his previous opus make the best general reference on ruby & sapphire published to date though I do wish Hughes had come up with a title that was not so similar to his first book.

HughesCollectorBook

As a bibliophile, I was particularly taken by his section on books and gem libraries.  Despite the fact that I have written and read extensively in the field and own a voluminous library, Hughes always seems to come up with obscure sources which send me scrambling back to that library to search for the odd passage and just as often to online sellers of rare books.

The photography appears to be a Hughes family project with contributions from his wife Wimon Manorotkul and his daughter E. Billie Hughes.  They are a truly formidable trio.   The images are uniformly beautifully composed, at times dramatic and always provacative. 

Never dry, Hughes offers a lively, if somewhat self-conscious and definitely idiosycratic narrative that is rarely off-putting and never dull.

If you missed the first volume here is an opportunity and if you didn't this book will complete the set.  Ruby & Sapphire, The Collector's Guide, published by The Gemmological Institute of Thailand (GIT), is not readily available in the U. S. Still, given its quality and the limited print run and the money saved by direct marketing, it is well worth paying the high shipping costs to get the book sent directly from the author.   

 

 

Terra Garnet: 

TGcoverWTo round out the year's splendid offerings, Vladislav Yavvorskky has brought forth his second book in his Terra series, Terra Garnet.  Like its predecessor, Terra Spinel (now out of print), this georgeous volume is sumptuously produced with fabulous images of some of the finest garnets on earth.   

VYportraitW

Vladislav Yavorskky

The accompanying text is written by Richard W. Hughes and Jonas Hjornered.  If the reader is seeking an in depth gemological analysis or history of garnet as a gemstone it won't be found here.  Other than brief introductions to garnet and a bit on producing countries, the commentary consists of short captions.  This book is all about the pictures and what pictures they are.  

Yavorskky is a talented photographer and Terra Garnet puts this talent on display. His photographs of gem mining and producing areas capture the essence of these often remote areas and will give the reader a real taste of the hard life of those who seek out precious gems.  

In these photographs, taken over twenty years, Yavorskky often juxtaposes the cut stone against the original rough material, visually initiating the reader in the awe inspiring metamorphosis that takes place as these beaufiful products of nature are transformed by the hand of man.  In the past decade, color printing technology has taken a great leap forward and this book showcases the best of it.  

One caveat: I have been adminring Vlad Yavorskky's gemstones for many years and though they are beautiful in person, many of these shots appear overproduced and likely to establish an unrealistic paradigm in the mind of the unintiated consumer.

Like Hughes' book, Terra Garnet is not available through standard channels.  This turns out to be a good thing, The book is so beautifully and expensively produced that its price would be substantially more if it was.  The reader as advised to act quickly.  Terra Garnet is available direct from the publisher


 

 

 

Colored Diamonds; Really The Blues Part II

by Richard W. Wise, G.G.

© 2013

Fancy diamonds are back in the news, another auction record broken  This time its blues.  At Bonhams of London, a 5.30-carat fancy deep-blue diamond set a world auction record for price per carat when it sold for approximately $7.3 million, or $1.8 million per carat bettering the previous record of 1.68 million per carat.  I recall a 5+ carat Fancy Deep blue emerald cut I viewed at the Las Vegas show some five years ago with an askiing price of 1 million per carat, quite a nice appreciation.

Some might argue that auction prices do not reflect actual market prices, but in the case of fancy colored diamonds and colored gems such as important ruby and sapphire, auction prices set the market.  This is a pattern that began to emerge in the 1990s and accelerated in the early 2000s as retail buyers became a larger factor in the auction market.  Online auctions also have helped spread the word about important gem sales and in many cases, auction prices actually lead the way.

Update on The Wittelsbach:

Another famous blue diamond is The Wittelsbach, the largest blue diamond ever sold at auction.   I wrote about this gem previously,   After being recut and regraded from Fancy Deep Grayish Blue to Fancy Deep Blue and exhibited at The Smithsonian Institution side by side with The Hope, London dealer Lawrence Graff reportedly sold the gem for $80,000,000 or something over 3.3 million per carat.

  Of course there are a number of Fancy Deep Blue diamonds over five carats but no others over thirty excepting The Hope.  Weighing in at 31.06 carats, The Wittelsbach commands a price based on the extreme rarity of a colored diamond of this size.

Buying Gems on The Internet; Picture Perfect

by Richard W. Wise, G.G.

©2012

Everyone is familiar with the old sayings; seeing is believing and a picture is worth a thousand words. In the internet age, however, I'd suggest prospective gem buyers embrace another old saying, "believe half of what you see!" Yes, thanks to Photoshop coupled with the ability to select a broad range of lighting options at varying color temperatures, a picture can tell a thousand lies.  Despite this, gem buying on the internet has increased a thousand fold aided by a crop of gem forums where hobbyists, prospective grooms and gem collectors gather to share information and critique gems on offer.

Many of the participants in these forums believe that a gemstone is just another commodity that qualities are uniform and prices follow some sort of median so that if most of the 1 carat sapphires they see online are $3,000 a carat then any stone with a price tag above that number is, by definition, expensive and overpriced.    As I have said in my book, Secrets of The Gem Trade, and other places, this is simply not true.  The prospective buyer who limits himself to images and median prices is doubly mistaken assuming that quality is his goal.  This myth is reinforced by largely untrained  online gurus who claim the mystical power to judge the quality of a gemstone by simply evaluating an image and by consumers who simply want to believe them rather than doing some of the tedius work of actually comparing stones.

As gemstone approach theoretical perfection in color/cut/clarity and crystal, smaller differences in those criteria make for larger and larger differences in price.  At the same time, those subtle difference are extremely difficult to capture in an online image.  An image can tell a lot about a gemstone with regard to clarity and color, I can often see enough to pass on a given stone, however, I cannot see enough to make a firm buying decision.  From this point on, actual comparison is absolutely essential.

Unrealistic Expectations:

Of Off center Culets and Tilt Windows:

The Making of a Masterpiece VI (Part 2)

The finished pendent, steps in making follow.

The finished pendent, steps in making follow.

The wing is constructed of separate elements to give it maximum definition. Here an individual "feather' has been cut out, drilled for the gem and is prepared to be domed.

The wing is constructed of separate elements to give it maximum definition. Here an individual “feather’ has been cut out, drilled for the gem and is prepared to be domed.

DappingBlock1

 

Here goldsmith Michael Corneau uses a steel punch to curve a single feather of the bird's wing.

Here goldsmith Michael Corneau uses a steel punch to curve a single feather of the bird’s wing.

Ancient Technique of Sand Casting:

Truly handmade jewelry is made in the ancient manner using the metal itself.

Modern commercial and some so-called handmade pieces are actually carved in wax and then cast using the cire perdue or lost wax process.  The more ancient method is sand casting.  The approach is similar, a model is made and it is impressed into a crucible.  In each case the molten gold is poured into a vacancy.  Once a mold is made, lost wax can be used to produce multiples.

The total time required for Michael Corneau to produce the Peacock Pendent was 212 hours.  This did not count, of course, the time spent developing the concept, discussion and selection of gemstones.

WaxInSand

PouringGoldSand

Sand casting the peacock’s body: Molten gold is poured into the depression made by removing the model from the sand.

Setting the gems: Once the feathers have been dapped out and soldered together and the cast body has been finished and soldered to the tail, gem setting can begin, the method is known as thread and bead setting.Peacock Pendant: Micro view, all gems set.

Setting the gems: Once the feathers have been dapped out and soldered together and the cast body has been finished and soldered to the tail, gem setting can begin, the method is known as thread and bead setting.Peacock Pendant: Micro view, all gems set.


by Richard W. Wise, G.G., A.S.G. ©2012 all rights reserved.

Treasures from Trash, What is Art?

Head of The Phoenix.  The total length of this sculpture by Chinese artist Xu Bing is 110 feet.  The weight, 12 tons.

Head of The Phoenix. The total length of this sculpture by Chinese artist Xu Bing is 110 feet. The weight, 12 tons. The head is a commercial jack hammer. Photo: R. W. Wise

by Richard W. Wise, G.G., A.S.G.

©2013 all rights reserved.

At 110 Feet long and weighing in at 12 tons each, the artist Xu Bing’s Phoenix Project currently on view at Massachusetts Museum of Contemporary Art is impressive.  It is particularly interesting given my last post in which I asked questions regarding art and the use of precious materials.

Once you get beyond the shear size of them, what is particularly striking about the twin bird sculptures suspended from the gallery ceiling, is the fact that they are totally built from construction waste.  That’s right junk!

In my last post, I showed a beginning series of images of a 4 x 1.75″ Peacock Brooch constructed of 22k gold, 18k gold, black opals, rubies & sapphires and asked the rhetorical question, can a piece of jewelry constructed out of precious materials be considered art?  Many critics hold that the jeweler’s art, if it is art at all, is a minor one.

So, when my wife Rebekah and I walked into the gallery Sunday, what to my wondering eye did appear but a huge, in fact two huge works of art made exclusively of junk, the very antithesis of or you might say the other side of the coin.  Junk had obviously been used as a material to create art, what did that say about the use of gold and gemstones?

Close up of the wing of the Phoenix, note the use of various types of waste found around construction projects.  Xu Bing lived in the U. S. for many years, when he returned to China he was struck by the magnificence of some of the new buildings going up contrasted with the dwellings of the poverty striken workers who built them.  Photo:  R. W. Wise

Close up of the wing of the Phoenix, note the use of various types of waste found around construction projects. The artist used re-bar, flashing, discarded gas bottles and shovel blades among other things to construct his birds. Xu Bing lived in the U. S. for many years, when he returned to China he was struck by the magnificence of some of the new buildings going up contrasted with the dwellings of the poverty striken workers who built them. Photo: R. W. Wise

The first thing that struck me as that the constructions themselves were quite beautiful.  It was necessary to focus, to draw the mind away from the contemplation of these wonderful works of art to be able to discern the method and materials of their construction.  First you see the whole, only later the parts.

What makes a material precious?  It is largely a question of attitude. Gold has been valued from the beginning of recorded time.  You need only to see and touch a natural gold nugget to understand the material’s appeal.    First the color, in its pure form, gold is a striking orange-yellow.  Its weight is reassuring, its touch sensual.  Are these attributes simply too seductive to the senses, do they submerge the artist’s intention and make it impossible to convey meaning?  Certainly it doesn’t help.

Given the tactile and visual qualities of gold and the connotations of wealth associated with it, it is clearly impossible for anyone to view the object qua object without reference to the material of its construction.

When you view Xu Bing’s Phoenix you are struck by his achievement.  When we view the Peacock Brooch are we simply overwhelmed by its glitter?

All That Glitters; The Peacock Pendant:  22k gold, 18k gold, opals, rubies, sapphires, spessartite garnets and natural Mississippi Pearls.

All That Glitters; The Peacock Pendant: 22k gold, 18k gold, opals, rubies, sapphires, spessartite garnets and natural Mississippi Pearls

Still, there is no denying the beauty and appeal of the Peacock Pendant.  Each bird appears to float, each has a distinct attitude, the tiny gems twinkle in the light and the peacocks magnificent  tails’ wrap themselves provocatively around a golden bower.  They eye is, of course, drawn to the center stones.  The two opals exhibit a fabulous flashing pallet of color.

NEXT POST, The Making of a Masterpiece VI (Part 2) MORE IMAGES, STAY TUNED.

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The Making of a Masterpiece VI (part 1)

22k/18k hand fabricated Peacock Pendant. The piece is accented with two black opals from the Moonshine Field at Lightning Ridge as well as rubies, sapphires, natural Mississippi pearls and spessartite garnets. Designed and handmade by R. W. Wise, Goldsmiths, Michael Corneau, designer/craftsman.

22k/18k hand fabricated Peacock Pendant. The piece is accented with two black opals from the Moonshine Field at Lightning Ridge as well as rubies, sapphires, natural Mississippi pearls and spessartite garnets. Designed and handmade by R. W. Wise, Goldsmiths, Michael Corneau, designer/craftsman.

by Richard W. Wise, G.G., A.S.G.

©2013  all rights reserved.

What is art and is the work of the goldsmith an art at all or merely a craft?  This is an ancient debate.  Some would argue that the use of precious materials, as opposed to more mundane materials, such as paint and canvas disqualifies the metalsmith and his product from the status and stature of the fine artist.  Jewelry is all about the materials, gold, platinum, gemstones, design being viewed as a secondary concern.  The objective of the goldsmith, is to decorate the body and decoration is not art.

That the piece pictured left is decorative cannot be denied.  Its inspiration hails from the Art Nouveau Movement (1900-1910), with a design iconography that evolved out of the Arts & Crafts Movement, which paradoxically stressed the use of simple non-ostentatious materials and hand craftsmanship.  Like Arts & Crafts jewelry, Art Nouveau jewelry utilized naturalistic design,  but whereas Arts & Crafts practitioners emphasized the use of unusual and relatively mundane non-precious materials,  Art Nouveau eschewed the ideological and abandoned the mundane but retained the emphasis on the naturalistic embracing a a more feminine, sensuous vocabulary partially through the use of precious materials.

It is no mistake that the Art Nouveau Period parallels what has become known as The Gilded Age—neither saw anything wrong for sumptuous decoration for its own sake.  Plato reduced art to beauty.  Is decoration art or is it something else, I guess you will have to decide.

As is often the case, we began with a client, a magnificent pair of black opals and an idea.  We worked with the client over several months.  The following images illustrate far better than any words the development of the concept.

Birth of  A Concept:

The concept began with a pair of black opals the two peacocks, a perennial part of the Art Nouveau design lexicon.  The peacock has been used as a symbol from the time of the ancient Greeks.  However, in this case, it seemed particularly useful as a naturalistic excuse to show off the the bird’s plumage using a rainbow of colored gemstones.

Second Preliminary sketch.

Second Preliminary sketch.

Completed sketch.

Completed sketch

 

Accenting Color

Finding accents for gem opal is always a challenge.  Very few gemstones find a simpatico with opal.  In this case; ruby and blue sapphire worked very well, picking up the corresponding hues in the opals, but when it came to the orange tones in the opal, orange sapphire and diamond simply did not work.  The only gemstone that the opal would accept was spessartite garnet. Here is the preliminary

layout:  In the next post, I’ll share some more images including the steps involved in the hand manufacture of this beautiful pendant.  Stay tuned…

PeacockGemLayout3

 

Natural Heliodore, Golden Beryl from Connecticut

10986:  2.11 Carat pear shaped brilliant cut with exceptional vivid color and crystal.

10986: 2.11 Carat pear shaped brilliant cut with exceptional vivid color and crystal.

by Richard W. Wise, G.G.

© 2012  All rights reserved.

10987 A 1.74 Carat ovall brilliant heliodore from the Roebling/Merryall MIne, Litchchfield, Ct.  The gem exhibets an exceptional vivid medium toned golden hue.

10987 A 1.74 Carat oval brilliant heliodore from the Roebling/Merryall Mine, Litchfield, Ct. The gem exhibits an exceptional vivid medium toned golden hue.

Golden Beryl; An American Gem

In the 19th Century, the state of Connecticut was known as a major source of golden Beryl.

In the past few years a fair amount of golden beryl a.k.a.  heliodor has entered the gem market.  Material currently in the market is coming from Pakistan, Brazil and Ukraine and although there is no reliable gemological test that will prove irradiation, much of this material is thought to be enhanced by gamma radiation, a method that leaves behind no footprints.  Of late there have been misguided attempts to cash in on the gem's more famous sibling by re-labeling the gem as "yellow emerald."

The continental United States is not known for its gem wealth though historically both California and especially the New England states have  produced some exceptional gems.  In the 19th Century, Maine was known as a repository of gem quality tourmaline, some beryl and amethyst.  Most of the gems found in New England are of pegmatic origin the result of long super-hot magmatic fingers working their way up through cracks into the country rock causing localized melting into a chemical stew and its constituents, where beryllium oxide was present,  might reform into beryl crystals.  Many of the most important strikes were found in Maine including the famous Mt. Mica Mine which resumed operations in 1990 after a long hiatus.  Pegmatites are found in all the New England states excluding Rhode Island and are particularly numerous in Maine and New Hampshire.  Gem mining was in most cases simply a byproduct.  The mines were mainly exploiting mica, Beryllium and feldspar.

Beryl is a family name whose best known offspring are emerald and aquamarine.  If a beryl is pink it is known as morganite if red it is called bixbite or simply red beryl.  In the 19th Century, golden beryl was quite rare and Connecticut was considered a major source.  The term heliodore, from the Greek meaning "gift of the sun" was originally a trade name made up to describe yellow beryl from Southwest Africa.

"A Gift from the Sun," Gem Mining in Connecticut:

Few realize that the George Roebling or Merryall Mine located in Litchfield County, Connecticut was, historically, one of the most productive and commercially important gem mines in the United States.  This mine opened in 1880 as a feldspar and mica mine and worked intermittently until 1955 when it was closed.  According to the late John Sinkankas, Merryall is known to have produced particularly fine beryl in shades of blue, yellow and green including a 40.44 blue-green heart shaped gem that now resides in the Smithsonian.  The mine produced some sizable aquamarine, but most of the heliodore production was limited to very small faceted gemstones.

We recently acquired a few particularly fine rough examples of natural unenhanced heliodore, portions of a single large crystal, sourced at the Roebling/Merryall Mine site from a pile of unsorted mine run material in the early 1980s.  The crystal was inside a large boulder.  This material has been precision cut into a few lovely heliodore gems.  These gems are flawless to the eye, exhibit a particularly fine crystal structure, a high degree of transparency and a vivid pure yellow hue and perfectly cut by our lapidary.

10987 Rough material from which the 1.74 carat oval, 10987, was cut.

10987 Rough material from which the 1.74 carat oval featured at the beginning of this post, 10987, was cut.

As Sinkankas points out, very little of the material sourced from this location is of gem quality never mind eye-flawless material.  Mine run material containing 1% Beryllium is considered a rich deposit.  Gems from this site have not been on the market in many years. For the gem collector, this is an or for the jewelry lover looking for a lovely vivid yellow gemstone, this is an opportunity to buy American and acquire a particularly fine gem from a truly rare source.

Gemstone Cut Grading; Distinctions Without a Difference II

by Richard W. Wise, G.G.

©2012 all rights reserved.

Of Tilt-Windows, Off-center culets and other minor issues:

255.1

The image of the gem quality 1.44 carat alexandrite might lead the uncritical observer to conclude that the gem is windowed. What the gem is actually exhibiting is some extinction beneath the table. In a perfect world, both are minor faults, but we are talking about the rarest gem on earth. In the world of true rarity, beauty not mathematical perfection of symmetry is the ultimate criterion.

The first time I ever heard  the term tilt-window was on the Pricescope forum.  As you know, a window is a part of the gem when viewed face-up that exhibits transmitted light.  Windows are almost always found right beneath the table.  A quick test is to place the stone over a piece of newsprint.  If you can read the print, you are looking through a window.  Windows are the result of a shallow pavilion, a too shallow depth to width ratio.  Windows are considered faults because they are a portion of the gem that does not sparkle.

Gem cuts are designed and engineered to be judged face-up with light perpendicular to the table.  Tilt the gem away from the perpendicular and every gem other than a briolette will exhibit a window. Ironically the more precise the cut, the more likely the gem is to window when tilted as little as five degrees from the perpendicular.  Some gems, particularly those with a bit of fat around the pavilion, may exhibit some brilliance when tilted as much as ten to fifteen degrees from the perpendicular.   What cannot be eliminated must be embraced.   A tilt window, forgetaboutit!

Grading; From Minus To Plus:

Gems with bulbous pavilions are often criticized for being overweight, meaning that the stone’s face is smaller than it would be if the stone was perfectly cut.  The irony here is that such stones may actually exhibit a greater arc of brilliance which contributes to the beauty of the gem.  Once the eye is four to five feet from the gem, the overall brilliance becomes the real issue, not the stone’s mathematical diameter.    Broader bellies also extend to the length of the light path and may enrich the  color (hue, saturation and tone) of the gem.

In another Pricescope thread, one ubiquitous poster put a link to an alexandrite (pictured above) on my website and criticized me for the failure to disclose an off-center culet.  How did this forum member determine that the stone had such a terrible fault?  The page included a side view image of the stone face-down.  If there was an attempt to hide the fault, it was hidden in plain sight.  http://www.rwwise.com/products/id,255   Unfortunately her interpretation of the image was quite wrong.  The stone does not have an off-center culet.  What the forum member saw was a very minor symmetry fault, one side of the pavilion has a slight indent coupled with a tilted crown which when placed on a flat surface caused the culet to appear off-center.  And if the gem did have a slightly off-center culet, so what!  We are talking about one of the earth’s rarest treasures, a gem quality alexandrite!

Each Gem Is an Individual with a distinct personality and should be judged on its merits:

Gem aficionados usually begin their love affair with the colorless diamond.  They learn the famous 4 C’s and attempt to apply those criteria, namely color, clarity cut and carat weight uncritically to colored gemstones.  As I have said elsewhere all Cs are not created equal.  In the connoisseurship of colorless diamond, cut is the 1st and most important criterion.  Diamonds have no color, they are all about  brilliance and sparkle, so naturally cut, which delivers sparkle is the most important single criterion.  I knew a neophyte jeweler once who was not satisfied with eye-flawless sapphires, he demanded that all of his sapphires be flawless under 10x magnification.  The problem, without inclusions it is almost impossible to determine if a stone has been enhanced and determination of geographic origin is absolutely impossible.

Colored gemstones as their name suggest are all about color and cut is, at best, a secondary consideration.   An off-center culet in a diamond would be a major symmetry fault and materially effect price.  In a colored gem, an off-center culet in and of itself is a minor fault which has no effect on price.  Why do such things exist?  A culet might appear off-center for a couple of reasons.  The lapidary may have removed a potentially eye visible inclusion or have placed the culet slightly askew to smooth out color zones so that the zone does not appear in the gem when viewed face-up.

It should be remembered that colorless diamonds are not truly rare.  The introduction of cut and clarity scales that have nothing to do with beauty are more about creating the appearance of rarity than the thing itself.  The connoisseurship of gemstones requires discernment and careful contemplation.  Gems cannot be accurately graded by image.  The aficionado should beware attempts to reduce it to a formula or a check list.

Gem Cut Grading; Distinctions Without A Difference

The diagram shows the proper angle for viewing an asymetrical gemstone.  The bottom half of the gem is evaluated, the gem is then turned 180 degrees and the other half is judged for percentage of brilliance, the two percentages are then totaled.

The diagram shows the proper angle for viewing an asymetrical gemstone. The bottom half of the gem is evaluated, the gem is then turned 180 degrees and the other half is judged for percentage of brilliance, the two percentages are then totaled.

This matche pair of carat sized blue sapphires exhibit off-axis refraction also known as extinction.  The dark areas move as the gem moves partially defilning the positive areas of scintillation

This matched pair of carat sized blue sapphires exhibit off-axis refraction also known as extinction. The dark negative areas move as the gem moves partially defining the positive areas of sparkle (scintillation) in the gems

I wandered over to one of the major gem forums this morning.   One of the members was talking about a phenomenon he called “shadowing.” This poster defines shadowing when a gemstone exhibits brilliance across half the stone when the stone is held off axis, that is not perpendicular to the light source, he was looking for a cure.

A Non-Issue:

This is a good example of a non-issue.  Non-symmetrical cuts, rectangle, oval, pear viewed under a single beam light source will always show brilliance across half the face of the gem when the stone is tilted away from the perpendicular. Why, because the gemstone is not symmetrical and therefore treats light in a non-symmetrical fashion. In the cuts just mentioned, some facets particularly the pavilion facets which are responsible for delivering brilliance, cannot be uniform.   Some are larger, some are longer therefore light hitting these facets will refract in an irregular fashion.  Symmetrical cuts, rounds and square cushions, by contrast have uniform facet patterns and do not suffer this phenomenon.

For this reason, asymmetrical gems are graded under a single light source, viewed at at a 45 degree angle away from the light source angled toward the eye.  At this viewing angle, half the gem, the bottom half is potentially brilliant.  The percentage of that half is then compared with the other half when the gem is rotated 180 degrees and viewed a second time.  Add the relative percentage of each half and voila you have the total percentage of brilliance.  In colored gemstones, 80% brilliance is considered excellent which means that at any given time, 20% of the gem will exhibit extinction.

One trick for viewing the brilliance of the entire stone at once is the use of sky light.  Turn your back to the sun and view the gem at the same 35 degree angle toward the eye.  In this position the light filtering around the body of the viewer should light up the 100% of the gem.  Any lack of brilliance in this position is a fault and should be subtracted from the theoretical 100% to arrive at the percentage of brilliance.   In most cases, gem photographers correct for this phenomenon by photographing gems with non-symmetrical  outlines by using  multiple light sources.

A Little Extinction Contributes To A Gem’s Beauty

Extinction is another much misunderstood phenomenon. I am often asked, particularly by members of this forum, if a particular gem shows extinction. First lets define our terms, what is extinction. This phenomenon is caused by off-axis refraction. When light enters a gemstone, it enters the crown and reflects internally off the pavilion (back) facets and eventually back through the crown to the eye. Inevitably some light refracts at an angle that is not toward but rather away from the eye, the greater the angle the more extinct it becomes, in a tonal continuum from gray to black.

All faceted gemstones without exception exhibit extinction, no extinction, no scintillation. the great German philosopher Hegel said determinatio est negatio. which when reduced to simplest terms means g all positive requires a negative.  Sweet has no meaning without salty, good does not exist without evil, etcetera.  So too with gems. Scintillation, sparkle is the result of light being broken up into pieces, tiny scintillas of light that are refracted back to the eye in little pieces. Between those pieces is darkness, extinction. Want a gem to light up like a flashlight with no sparkle, eliminate extinction.  Some degree of extinction is therefore required as contrast.

Extinction As A  Fault:

Extinction can have other causes as well, dark is the absence of light.  Gems lacking transparency will often show what one of my clients once called a “heart of darkness” at the center of the gem beneath the table.  This is particularly prevalent in sapphire and the cutter will often cut a window to let in light through the culet, the apex of the cone shaped pavilion of the gem.  So while some extinction is desirable, in fact necessary to the beauty of the gem, large areas of extinction are a definite and definable fault.

Evaluating Gem-e-Wizard; Gem Grading/Pricing Software

©2011 by Richard W. Wise, G.G.

First off, Gem-e-Price is the first grading/pricing software that I have evaluated and working with it was a lot of fun.  With the recent addition of colored diamonds, Gem-e-Price is now able to offer a price structure for just about all species and varieties of colored gemstones.

Gem-e-price offers three ways to approach the evaluation/pricing process.  I say evaluation because, although gem-e-price is sold as pricing software, the ability to select quality is a necessary precondition for determining price.

Ease of Use:

The software is easy to use.  First you are presented with a fairly clean screen with buttons and drop boxes.  There are three tabs;  Fancy Search, Price List and Price Calculator.  The default screen, Fancy Search allows you to select a gem variety, size, shape, weight, clarity, treatment.

Gem-e-price Home screen

Gem-e-price Home screen showing range of colors in yellow diamond.

Unfortunately it didn’t take long for the first bug to appear.  Once you select “color” (primary hue) and “modifier” (secondary hue) and move on to shape, you quickly realize that though you can select your shape from a graphic series, only two shapes will actually appear in the gallery, select round or square cushion, choose any other shape and square cushion is shown.

The images, which in the colored diamonds section covers the basic grades, fancy through fancy dark,  are not pictures of actual gemstones or photographic images at all, they are graphic representations.  When I first saw these during the introduction of gem-e-price for colored gems, I referred to them as grading by cartoon.  However, one function of the software helps overcome this lack of veracity to some degree.  Once the color has been selected, say yellow, the “Fancy Ruler” button to the right will take you to a screen with a spectrum representing all colors, from there a “Select Color” button in the center of the screen takes you to a new screen with all permutations of the given color (hue): brownish yellow, brown yellow, orangy yellow and so forth.   You get a good relative overview of what the graphic range is supposed to represent and is useful for honing in on the appropriate nuance of color.

Gem-e-price screen showing range of primary and secondary hues in pink diamonds.

Gem-e-price screen showing range of primary and secondary hues in pink diamonds.

It also provides you with a more or less universally accepted color descriptive  shorthand, e.g. VpB (vivid purplish blue).  I should add that you are able to upload, at the home screen, an actual image of the diamond that you wish to compare and that image follows you from screen to screen.

Nomenclature Issues:

Is the pricing accurate?  As Shakespeare said, “aye, there’s the rub.”   The answer is yes, no and sometimes.  I compared the Gem-e-price with a couple of my own diamonds, then called colored diamond expert Stephen Hofer author of Collecting and Classifying Coloured Diamonds and compared various price lists, pink, gray and blue diamonds generated by the Gem-e-price software.  The prices made no sense at all until in a conversation with Gem-e-price developer, Menahem Svedermich, he revealed that the price is pegged fairly low.  This will require a bit of explanation.

The point I make in my book, Secrets Of the Gem Trade, is that all fancy vivid diamonds are not created equal.  GIA’s colorless diamond grading system has 24 grades, the GIA colored diamond grading terminology has only between 5-7 depending upon the hue.  These are fancy light, fancy, fancy intense, fancy vivid, fancy deep and fancy dark. In the vivid category, for example there can be high, medium and low vivids depending upon the saturation/tone of the hue.   Gem-e-price assumes a 1-5 saturation grid at each level and pegs its price to level 2.  Why not the median?  Good question!  Well, one week later, Gem-e-price has been updated, it now sports three price levels for each color grade, Regular, Fine and Extra-fine categories and these have helped to better define price levels.

Pricing Accuracy:

With Hofer’s help I took a look at a one carat Fany Intense Pink  diamond( FIP).  A two thousand dollar spread, in pink diamonds, hardly worth mentioning, the price was spot on.  I then went to a 0.70  FVY-O from my own inventory.  This is a problem stone, The GIA grading report calls it Y-O, to me its a orangy yellow (oY).  So, I tried it both ways.  The Yellow-Orange price was way out of the box, the Orangy-Yellow was pretty close to my actual cost.  Next I tried a 1.75 Fancy Intense Blue IF which Hofer described as a top stone.  The Gem-e-price was between under Hofer’s price by between 100-200,000 per carat—sounds like a lot but we are talking blue diamonds here so it is fair to say that Gem-e-price is in the ballpark.  I did some further work, switching over to colored gemstones I priced out emerald, ruby and sapphire.  The emerald and sapphire prices came out in the zone, the ruby price, we are talking super-unheated-gem in one carat sizes came out very high.  I asked Antoinette Matlins author of the second best book on colored gemstones—opps there goes my Bonanno award—she checked my price and reported results that were similar to mine.

Overall Evaluation:

Overall I like it.  Is it perfect, no!  It is designed for professionals, in the hands of someone without a wealth of experience it could be a potential disaster, but then what isn’t?  Gem-e-price is a useful tool, its got a few bugs, but it is getting better, Svedermich and his team made adjustments as I worked and will, I am sure, continue to improve the product.  I like the price grids!  A subscription with monthly updates is $300.00 per year and, in my opinion, well worth the price.