Category Archives: gemstones

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an injudicious use of MSWord’s find/replace shortcut the word “diamond” in the last two thirds of the manuscript has been replaced by “pearl.”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.   

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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


 

 

 

Online Gem Sale

6162  We have several carat size, gem quality blue sapphires

6162 We have several carat size, gem quality blue sapphires

We rarely have sales.  In fact, I don’t remember the last one.  However, in honor of the recovering economy we have decided to put all our loose gemstones on sale.  This applies to everything other than the “Sale Gallery”  Just go to the top of this post and place you cursor on Gemstone Gallery.  You can then follow the index.

Currently gems priced over $5,00o are not priced.  In any case we do not have a market basket—people who like gems rarely buy with one click—so give us a call:  413.637.1589 (800.773.0249 and Rebekah or I will give you the details.  On sale gems are not sent “on approval” and returns will only be accepted if the gems are damaged or not as advertised and they are as advertised.  The sale goes on until August 1st.

0418  Mandarin (spessartite) garnet.  3.27 carat.  Retail price:  $1,962.00.  SALE PRICE:  $1471.50

0418 Mandarin (spessartite) garnet. 3.27 carat. Retail price: $1,962.00. SALE PRICE: $1471.50

2126:  Black Opal.  Retail Price:  $14,000.00 ONLINE SALE PRICE:  $10,500.00

2126: Black Opal. Retail Price: $14,000.00 ONLINE SALE PRICE: $10,500.00

Custom Design, Why Bother?

Recently I had a spirited discussion with a client about custom design.  She wasRebekah's-ring-side-PW interested in buying a fine stone, but really could not see any value in a handmade setting.Rebekah's ring front-P I grew up in a generation that valued the work of the hand.  When we first opened our business in 1978, we basically worked as custom goldsmiths.  We made an awful lot of wedding rings for clients interested in having a unique symbol of their unique relationship.

Today, use the words “handmade original” and the client’s eyes glaze over.  Nobody cares, its really all about name brands and low prices.  “If it isn’t Cartier how can I get it cheaper?”  There is also some confusion about the words, custom design, some people think that it is synonymous with handmade, which it is not.

Why Is Handmade Better Made?

Good question.  Why would I rather have a badly handmade ring in preference to a well made production piece?  The answer is, I wouldn’t.   However, assuming a fine craftsman and a well crafted mass-produced piece, whats the diff?

The art is in the process.  You buy a fine sapphire and you want a three stone ring.  When a craftsman makes a piece of jewelry the process itself is part of the creative effort.  As any craftsperson will tell you, during the making process the piece begins to speak to you in many subtle ways.

Consider the center stone.  Enhancement is part of the jeweler’s art and the crafting of the actual setting is very important.  I have seen gems made more brilliant or deadened by the setting.   A goldsmith can build a setting that will make the color deeper or lighter or increase or decrease its brilliance and scintillation.   If you have a $10,000 stone, spending an extra $500 to make it look like a $15,000 stone makes a certain amount of sense.   Recently we reset a 7 3/4 carat Burma sapphire.  The stone was valued in the six figures.  The setting actually made the already rich blue hue, even richer.

Computer Aided Custom Design:

The Lotus.  One of our signature settings.  Much more graceful than the standard four prong head, the Lotus can be shaped to correct any light leakage from the pavilion of the gemstone and improve the hue/saturation and tone and actually increase the brilliance and scintillation of some gems.

The Lotus. One of our signature settings. Much more graceful than the standard four prong head, the Lotus can be shaped to correct any light leakage from the pavilion of the gemstone and improve the hue/saturation and tone and actually increase the brilliance and scintillation of some gems.

Can a computer do custom design?  Certainly, but it rarely does.  A Computer Aided Design CAD program is only as good as the person manipulating it and that person is rarely a designer or master craftsman.    Just as an image drawn with a pencil and one painted with a brush looks different,  a  CAD design even when created by a talented designer, always bears the signature of the machine

Most “custom design” offered by commercial jewelers differs little from the process of selecting parts from a catalog, a center setting from column A, a shank from column B.  The difference is the parts are stored in a CAD library—a few mouse clicks and you have it—out pops a wax.   Commercial jewelers have embraced this technology, it saves having it in inventory.

Enhancement is part of the jeweler’s art.  The Lotus Setting pictured above is a good case in point.  This is one of our signature settings.   It can be shaped and proportioned to correct light leakage from the pavilion (bottom) of the gemstone.  Properly engineered (shaped and angled) the lotus can enhance the color (hue, saturation and tone) of a gem and/or pump up the brillance and scintillation of the gem.  In the sapphire ring at the top of this post you can see a square lotus that looks quite different from the drawing.   Can a lotus be made by machine?  Yes, but without the subtle engineering that requires the hand and eye of a master, it’s just another pretty face.

Custom handmade pieces are the creme de la creme of fine jewelry.   Art is a process that speaks to the maker.  Computer Aided Design (CAD) may technically fit the definition of custom but it rarely more than construction by catalog and it will never replace the eye and the hand of a fine artist/craftsman.

Color-change Garnet from Kenya

by Richard W. Wise, G.G. © 2009

IMG_7888_end_of_mgama

Mgama Ridge: Probably the source of the alluvial garnets found in the plain below. Photo Raja Shah, Color First

As Raja Shah tells us, it is a story typical of gem strikes from the plains of Kenya to the Australian outback.  While digging an outdoor privy, a ranch hand working in the gem rich region of Taita Tavita happened upon some unusual looking stones just a few feet under the surface and showed them to a local gem dealer.

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Garnet Mining: Photo: Raja Shah, Color First

Late last November I received an email from a budding young gem dealer living in Voi, a town near Tsavo National Park, half way between Nairobi and Mombasa.  He had a copy of my book Secrets and wanted to order more.  Further he wrote excitedly of a find of Alexandrite somewhere nearby.  “It looks just like the picture in your book.”   Well, sometimes where there is smoke, there can be fire.

Once the word got out, thousands of independent miners descended on the area and began excavating private land and even a section of adjacent road where according to Shah a number of fine stones were located.   The material is alluvial and appears to be spread out along a just south of Mgama Ridge (pictured above left)

ccgarnet1.83ctsprimary

1.83 carat color-change garnet sporting its daytime color

The strike turned out to be color change garnet, the best of which is similar to a find in the late 90s near the village of Bekily in southern  Madagascar.  Small amounts of color change garnet of this description has been showing up in East Africa for years.  The first example I saw was in   Kenya in early 1995.  A Nairobi dealer had a 1/2 carat oval that  bore an uncanny resemblance to Brazilian Alexandrite—the same teal blue peacock color that the Brazilian garimpeiros call peacock blue or pavão.

ccgarnet1.83ctssecondary

The same stone by night

Color change garnets have been found previously in Umba and Tunduru, Tanzania and in Embilipitiya and Athiliwewa, Sri Lanka and most recently on the island of Madagascar, in the southern part of the island near  the village of Bekily.

Although some of the garnets from the aforementioned location do have the much desired “Alexandrite like” color change, it was the discovery of the Madagascar location that brought reasonably large amounts of alexandrite like garnet into the marketplace.

IMG_7962_color_range

The range of color in garnet rough material from the new Kenya strike. All photos courtesy of Raja Shah, ColorFirst

According to Shah, the material comes in a range of hues with a predomince of brownish stones,  only about 5% of the material has the most desired red/purple to teal blue change and only about 5% of that material is suitable for faceting.

The Madagascar material has been described as pyrope-spessartite with small percentages of almandine and grossular.  This description is not particularly useful, relying as it does on a classification system that has been out of date for years.   Apparently the garnet for the new Kenyan strike, described as pyrope-spessartite with grossular, is chemically similar.  Again, like the Madagacar material, the color change is most likely associated with Chromium/Vanadium.

Giant Crystals found at Tanzanian Gem Fields

Chaos Reigns as Giant Red Crystals are Unearthed.


by Richard W. Wise

©2007

According to my writing partner, globe-hopping gemologist Vincent Pardieu, a new strike of giant red spinel crystals has sparked a gold-rush mentality in the gem fields of Mahenge, Tanzania. Hundreds of miners have abandoned other gem producing areas and descended en mass on the area where red spinel crystals weighing 20-50 kilograms have recently been unearthed.

Pink spinel has been mined in this area since the early 1990s. A few reds have been found but up until now the most notable stones have been the pink-orange stones, with a color similar to that of some “padparadscha” sapphires. The material is found in alluvial deposits. The rough typically consists of small octahedral crystals or fragments that weigh 0.1–2 grams about 30% of which is facetable. (photo: Jeff Scovil)

This latest find located this August consists of a primary deposit of spinel found in marble. They are finding decently formed crystals topping off at 275,000 carats about 5% of which is clean top faceting material. Highly saturated red stones between 20-50 carats have been cut.

Stay tuned, a detailed report by Vincent and myself should appear on the Colored Stone website: www.colored-stone.com within the week.

Whats a buyer to do?

Follow me on gem buying adventures in the pearl farms of Tahiti. Visit the gem fields of Australia and Brazil. 120 carefully selected photographs showing examples of the highest quality gems to educate the eye, including the Rockefeller Sapphire and many more of the world’s most famous gems. Consider my book: Secrets Of The Gem Trade, The Connoisseur’s Guide To Precious Gemstones.


“Wise is a renowned author… He’s
done a marvelous job of this first book, monumental work, a tour de force…My recommendation: Buy this book”.

Charles Lewton-Brain, Orchid

whether you like to know what the best colour is in Tanzanite, or how to grade a Diamond, you will find it in this book. No other book I read before dealt with this topic is such detail as Richard Wise’s masterpiece.”

A. Van Acker, FGA
Amazon June 2005

“Secrets Of The Gem Trade: The Connoisseurs Guide To Precious Gemstones by Richard W. Wise is an impressive new reference for dedicated dealers and collectors of gems, gemstones, and … pearls. Introducing and descriptively exploring each and every gem covered in the easy-to-use reference, Secrets Of The Gem Trade contains an illustrated summary of each stone inclusive of its history and general information, hue and tone, saturation, which may be noticed as the finest, an understanding of the particular gems rarity, and the caution for synthetics and how to depict them, however depending upon the stone there may be description of clarity, color fading, multi-color effect, etc. Secrets Of The Gem Trade is very highly recommended to anyone interested in gemology as a superbly organized, authoritative, comprehensive, and easy-to-follow reference.”

Midwest Book Review
April 2006

Only $37.95. Read a couple of chapters online: www.secretsofthegemtrade.com.

Buy it on Amazon: www.amazon.com

Lighting and Grading Gemstones Part II

LIGHT UP YOUR LIFE


by Richard W. Wise, G.G.
© 2006


What is the best lighting environment to view gemstones? In part I of this post I discussed the various lighting options and the pros and cons of each. In part II I will write about the lighting some of the world’s foremost gem experts and connoisseurs choose to both view and evaluate gemstones.

Among the experts opinions differ somewhat as to which “daylight” Kelvin temperature is best but each accepts daylight as the standard. Stephen Hofer one of the world’s most respected authorities on colored diamonds, maintains that 5500K works best for colored stones and 6500K is best for diamonds both white and colored. In his lab, which is dedicated to the evaluation of fancy color diamonds, all grading work is done under 6500 Kelvin fluorescents. C. R. Beesley, President of American Gem Labs in New York, prefers Vitalite a bulb manufactured by The Duro-Test Corporation with a Kelvin rating of 5500. “Most people don’t do their homework”, says Beesley, “comparing color temperature isn’t enough…” Beesley tested more than twenty different light sources in the process of developing his Colorscan colored stone grading system to gauge their actual effect on gemstones.

In 1994 GIA completely revamped its color grading system for colored diamonds, shifting from Veralux, a so-called low UV lamp rated at 6200K, (see Secrets Of The Gem Trade, p.60, fn) which remains its standard for grading colorless diamonds to a 6500K average daylight fluorescent bulb for grading colored diamonds. The lamp is manufactured by Kollmorgen Corporation. GIA also uses a 6500K for general research purposes. The Institutes use of light of this Kelvin temperature is in no way an endorsement of the use of this type of lighting by jewelers. According to James Shigley, GIA’s Director of Research, 6500 was chosen because it is a recognized standard used by color scientists. Little or no thought was given to enhancing the beauty of gemstones.

Incandescent and quartz halogen lamps can be made to resemble daylight with the addition of a blue filter. Duro-Test currently markets a “super-white halogen” that does the same job. I conducted a series of experiments with the Duro-Test product and found that this type of lighting does wonderful things for blue sapphire, aquamarine and amethyst, but does nothing to reduce the muddy look in blue and green tourmaline. “Super-white” induces a distinctly overblue look in rubies and tanzanite takes on an odd blue/violet multi-color effect quite dissimilar to its appearance in any other lighting environment. In diamond, “super-white” overly enhances the yellow/blue luster of the stone.

The problem!, filtered light makes for unintended results. Unfiltered fluorescent lighting can exhibit a relatively balanced spectrum when graphed on what scientists call a “Relative spectral power distribution” curve. Filtered lamps show spikes in this curve which are areas of color deficiency.

Another type of lighting called Neodymium is currently being marketed as a “full spectrum incandescent”. According to Roger Schoenfeld, a lighting specialist with Durotest, this is really a standard yellowish incandescent incased in a special glass invented in Sweden, which reduces yellow and generates a spectrum richer in red and blue. Neodymium is not a bad choice. It is excellent for diamonds. Neodymium is a bit better than standard quartz for sapphire and aquamarine though not as good as “super-white”. All three sources suppress the violetish to purplish secondary hue of the finer grades of sapphire.

Compared to daylight, neodymium works well with ruby, amethyst, emerald and tsavorite garnet. It is no worse with blue and green tourmaline which seems to be a true day stone, i.e. it looks its best in daylight and in daylight fluorescent 5000-6000K. Pink & red tourmalines do fine in Neodymium “full spectrum”, it does not produce the brownish secondary hue that most pinks exhibit in standard incandescent but, rather makes them look violetish. Tanzanite looks about the same as with quartz light; bluer than stan
dard incandescent and without the otherworldly quality of “super-white”.

Three or four years ago, Tailored Lighting introduced a 4700 Kelvin MR-16 lamp which has the highest Kelvin temperature of any incandescent bulb and may be the best solution yet for interior lighting. The new Solux lamp uses a new type of reflector to boost the quartz halogen lamp into the daylight range. This technology produces lighting with a fairly even power distribution curve (CRI) that shows no spikes in either the red or blue areas of the visible spectrum.

In a short, down and dirty test, Solux worked well with tourmaline, reducing the muddiness produced by all other incandescent light sources. Sapphire and ruby also benefited from this type of lamp, showing they’re colors in true daylight fashion. Solux also improved the diaphaneity of tanzanite. On the down side, Solux appeared to add a gray component to aquamarine and pink topaz which reduced the saturation and flattened the color.

Changing lighting environments have always been a problem for both buyers and sellers. You buy in one light, sell in another. Traditionally dealers who do extensive buying outside their offices have relied upon comparison stones, stones of well known color, which they carry or wear on buying trips.

I use two fixtures with twin four foot fluorescent lamps to give an overall daylight environment combined with several of the new Solux MR-16 4800K quartz halogen lamps in my own laboratory which doubles as a salesroom and consider this combination to be the closest possible to a true daylight environment. I use Duro-Test Vitalite in one fixture and Kollmorgen 6500K average daylight in the other. The use of the 6500K is to compensate for the 4800K Solux, to kick up the Kelvin temperature of the overall environment towards 5500K.

The combination of of daylight fluorescent with Solux works acceptably across the spectrum of gemstone colors. The fluorescents create an overall daylight environment and the Solux MR-16 provides the punch. This lighting temperature gives a balanced daylight color rendering when compared to New England north daylight. Several years ago, a German firm, System Eikhorst, introduced a lighting system based, in part, upon my recommendations. It includes both daylight fluorescent and Solux fixtures.

When making a purchasing decision it is important to identify the light source you are viewing the stone and to view the stone in as many lighting environments as can be found. Regardless of my geographic location at the time, I always compare each stone in daylight and 3200K incandescent to see how the stone reacts at both ends of the lighting spectrum.

If a consistent workable colored stone evaluation system is ever created, the lighting environment will of necessity be standardized. To achieve reproducible results, there are three variables; the observer, the gem observed and the lighting environment. The standardization of the lighting environment will remove one variable. This leaves one remaining variable, the observer. Either we must accept some nuances of subjectivity or build a gem grading robot replace to connoisseur’s eye and dictate our taste.

Light Up Your Life; Lighting and Grading Gemstones, Part I

LIGHT UP YOUR LIFE

Lighting and Grading Gemstones Part I

©2006

Richard W. Wise, G.G.

It used to be so simple, the brighter the light the better the light. You had the light from a fire and the light from the sun, that was it. In those good old days it was easy to figure out watt was watt! Today we have a myriad of options, “warm light”, “cool light”, “daylight.” Gem dealers are beginning to discover that the lights that make his rubies look like a pigeon’s blood may make his tourmaline look like a dog’s poop. As for the buyer, caveat emptor baby, check the bulb!

We are all familiar with the daylight standard: diamonds and colored gemstones are supposed to be judged in north daylight. Why?, because north daylight, specifically north daylight at noon is white light balanced between the red and blue spectrum. Sounds simple, but wait a moment! Dealers have long realized that the quality of daylight differs in locations throughout the world. North daylight at noon in Bangkok is qualitatively different from north daylight in New York.

The quality of natural daylight is affected by several factors, including latitude and air quality. In addition, the relative strength and color composition of daylight changes as the day progresses. “Don’t buy blue sapphire after 2:00pm“. That was the advice my Bangkok broker gave me on my first trip to Thailand. This dealer’s truism teaches a basic fact that as the day progresses the color composition of sunlight moves from yellowish into the blue range then toward red at sundown.

Color scientists measure color as a function of light temperature and express it in units called Kelvin (K). a light filament heated red will have a Kelvin temperature of 1000-1500K, orange like a candle flame has a color temperature of 1500-2500K, yellow between 2500-4000K, white as in daylight is defined as a range; 4000-10,000K. In practice, increasing Kelvin temperature reduces yellow and adds blue.

If we wish to get a true color rendering using the daylight standard we will want a bulb that produces average noon sunlight with its relatively balanced color spectrum with a color temperature between 5500-6500 Kelvin. Unfortunately, the Kelvin temperature of an incandescent lamp falls between 3000-3200. The new low-volt quartz halogens have a color temperature of only about 3200K. Light in this temperature range is distinctly yellowish and will enhance the look of stones in the yellow, orange and red range. It will add an attractive bluish hue to chromium-vanadium colored gemstones like emerald, chrome tourmaline and tsavorite garnet. However, some Emerald, particularly Zambian emerald, can look distinctly overblue in this type lighting and 3000k light tends to muddy the crystal (reduce the transparency) of iron colored green and blue stones such as tourmaline and sapphire.

Daylight equivalent lighting does exist in fluorescents but not in incandescent single point spot and flood lighting that is used by most dealers and jewelers to bring out the brilliance of a gemstone. Daylight fluorescent bulbs with Kelvin temperatures between 5500-6500 are available. These lamps are marketed, usually as “daylight” lighting by several companies under various trade names. Unfortunately fluorescent lamps generate a diffused light and produce insufficient punch, what scientists call lumens, to bring out the best sparkle in your gems. To further complicate matters, there is no recognized international standard for a daylight bulb. Each manufacturer decides for himself what to consider “daylight”.

Coming next: Part Two, Learn what types of lighting the experts favor, Stay tuned…

So, you want to learn more about lighting and judging gemstones? Read the book:


“Secrets Of The Gem Trade is very highly recommended to anyone interested in gemology as a superbly organized, authoritative, comprehensive, and easy-to-follow reference.”
Midwest Book Review
April 2006

www.secretsofthegemtrade.com