Monthly Archives: October 2006

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

Mozambique Cuprian Tourmaline, Part III

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Mozambique Cuprian Tourmaline, Part III

Purple Cuprian; A dilemma:

By Richard W. Wise, G.G.

“I know what you’re thinking. Did he fire six shots or only five? Well, to tell you the truth, in all this excitement, I’ve kinda lost track myself. But being as this is a .44 Magnum, the most powerful handgun in the world, and would blow your head clean off, you’ve got to ask yourself one question: Do I feel lucky? Well, do ya punk?”

Clint Eastwood

As tourmaline aficianados know, there are few truly rare colors of tourmaline. A pure yellow without a stong green secondary hue is quite rare and I have never seen a true violet but until recently, purple was the one spectral color that absolutely did not exist in tourmaline. Yes we had purplish reds but until last year when the Alta Lighona tourmalines from Mozambique entered the market, never a stone with a purple primary hue. (pictured above: 15.5 carat purple Mozambique cuprian tourmaline courtesy Pala International)

In early 1989 when the first curpian tourmalines from Paraiba appeared in the market in Brazil some were sold unheated. Most of these stones were a dark toned greenish “sapphire” blue, a “Thai sapphire blue” to be precise. In those days, blue was the most expensive, elusive and sought after color in tourmaline. Rumors whispered of a pure blue gem that was reputed to rival the finest in Burmese sapphire. This was the holy grail of tourmaline. I recall holding on to one parcel of natural dark blue Pariaba for several years before I burned them just in case the demand for the medium electric blue proved to be a passing fancy. Well, as we know it did not and when I finally did heat it, the result was a half dozen pure medium toned visually pure Carrribean blue gems that I sold at a substantial profit.

Since that time I have seen many examples of blue tourmaline including the famous Manoel Mutuca (described by Proctor as “sapphire blue” see Gems & Gemology, Spring 1985, p.11)) and Santa Rosa material but none (at least so far) with a true pure blue hue. Blue tourmaline always has a distinct greenish secondary hue which becomes quite evident when it is compared stone to stone with fine sapphire. Blue tourmaline can be exceptionally beautiful but it looks like tourmaline not sapphire.

To burn or not to burn or “Do I feel lucky? Well, do ya punk?”

With the entry of Mozambique curprian tourmaline we have a dilemma similar to the situation with the early Brazilian curprian tourmaline namely that some of the unburned material has a rich pure purple hue that reminds one of Siberian amethyst or fine purple sapphire. The difference is that unlike the rather dull greenish blue unheated Paraiba, this stuff is beautiful,

The Mozambique purples have a hue that is rich and pure. So, to burn or not to burn, that is the question, according to both Gene Flanigan from Precision Gems and Josh Hall at Pala International, these deep purples are also the best candidates for the oven, they heat to a neon pure medium “Paraiba” blue.

Some dealers have chosen the obvious solution. If you want a pure purple but burnable stone they will charge the same price as for the neon blue.(pictured above: unheated cuprian rough from Mozambique). Pictured below is an exceptional 1.89 carat custom cut Carribean blue cuprian stone cut from the center piece of rough. After and before; the first image shows the cut stone before heating. The second image shows the stone after the heating process was completed. The stone, currently available for sale at www.rwwise.
com was cut by Gene Flanigan a very talented lapidary artist from upstate New York. (Images courtesy Gene Flanigan: www.precisiongem.com)

Will purple tourmaline go the way of fine star sapphires that hardly exist anymore because they can be burned and faceted? I don’t think so, some of the fine purples simply possess problematic inclusions that make them risky candidates for burning. I found an 8.19 carat oval, a lovely example of Mozambique purple on my last trip to Asia. This stone faces up clean but under magnification shows long growth tube inclusions and cannot be burned. It is out having its picture taken and will be posted in a later blog. Logically purple cuprian tourmaline will have a two track price structure. Stones with a high degree of clarity under the loupe will sell for prices that may be double that for stones with certain types of inclusions whether visible or not.

Bits and Pieces:

I get lots of emails. Don’t think I’m not grateful. Every once in a while a real interesting one comes through the mailbox. take this on:

Position Available:

Dear Mr Wise,

We are Stargate, diamond trading division of Ebenhaezer Bank Consulting Group of Belgium, operating in thirty countries worldwide. We have read your blog regarding the appraisal of stones by qualified experts. We have constant need of qualified gemologists, expert in assessing ROUGH DIAMONDS, and have great difficulty identifying where they can be located.

We offer good working conditions, contracts, and a fair remuneration.

A special need has arisen in Bangui, Central African Republic, where we are currently (this week) accepting a large consignment. We require the services of a qualified gemologist, expert in rough diamonds, to assist our team there.

Would you be kind enough to assist us at your earliest convenience?

Yours sincerely,

Lucilla Arioti

Global Client Relationship Manager, EMEA

Stargate,

a division of Ebenhaezer Bank Consulting Group

Telephone: London +44 207 870 5389

I am not familiar with Stargate but believe the lady is serious. She even called and left a message on my machine. So if you are a gemologist in search of adventure give Lucilla a jingle. This time next month you could looking at sparklies and sipping pina colodas in beautiful downtown Bengui. As for myself I’d love to go along but I can’t give up my day job but when you get there be sure to drop me a line and oh do be sure to take along a flack jacket.

New Site with excellent online library of inclusions:

Got an email from a French gemologist: Marie-France Boursier-Brard. Ms Boursier-Brard has developed an excellent site with online images of inclusions. The site is quite comprehensive and well organized. Just click on: www.gemmes-inclusions.com

Check out my book Secrets of The Gem Trade; The Connoisseurs guide To Precious Gemstones: www.secretsofthegemtrade.com.

Now at 30% off just $27.95

“This book takes a much-needed sledgehammer to the industry’s conventional wisdom about what makes a gemstone precious, and in the process builds a solid foundation for anyone who wants to understand the true beauty and value of gemstones.”

Morgan Beard
Editor-in-Chief Colored Stone Magazine

Getting an Appraisal; Part II; The games jewelers play

Getting an Appraisal; Some Do’s and Don’ts

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Gems: Grading the Crème de la Crème, Part IV

By Richard W. Wise, G.G.

In the last three posts on this subject I discussed some of the rare characteristics that make certain gemstones so valuable. Value is naturally of great interest to the gem connoisseur/collector. How does a collector determine if he is paying the right price? In other words how does one go about establishing the value of one of a kind, ultra-fine gems?

First let’s establish what you don’t do. Don’t take the stone to your local jeweler even if he is a graduate gemologist unless he stocks comparable qualities of the gem in question. Most local jewelers know colorless diamonds but few have a working knowledge of colored gemstones. As with any sort of appraisal, the prospective appraiser should have a thorough day-to-day familiarity with the gem to be appraised.

Familiarity is easy enough to establish. If ruby is the gem at issue, go to the jeweler and ask to see his rubies. If he stutters and stammers and suggests he can have anything you want in the store in a matter of days, move on. If he doesn’t stock the stone, he doesn’t know the stone.

Watch out for the low-ball…

If the potential appraiser’s first statement, after you show him the gem and tell him what you paid is, “you paid way to much for that stone.” Run like hell! Why, because I guarantee that the next words out of his mouth will be: “I could have gotten you a similar stone much cheaper.” These are not statements made by a disinterested professional they are what they sound like, the words of a jealous competitor. The practice is so common it even has a name; low-balling. Some jewelers low-ball because they believe if they can discredit the competition, they will get the business. What actually happens is that the client becomes distrustful and the whole profession is discredited. If a low-ball raises a question in your mind; call the person’s bluff: “Ok, show me a better one, cheaper!.” Usually that will end it. Recently a client of mine went one better, he asked to be shown a comparable stone and agreed to buy it if the dealer came up with one. He still has my stone and is yet to see a match.

The next possibility is a professional appraiser. Over the past two decades gem and jewelry appraisal has become professionalized. There are three major appraisal organizations: The National Association of Jewelry Appraisers (NAJA) http://najaappraisers.com/ , The International Society of Appraisers (NSA) http://isa-appraisers.org/ and The American Society of Appraisers (ASA): http://appraisers.org/. These organizations have standards of education and codes of ethics to protect the client. In addition they use methodologies that provide some assurance of accuracy. However, I think the same standard applies. Does the appraiser have experience with the gem in question?

How often have I been asked for a: “Just off the top of your head, I won’t hold you to it” appraisal? An appraisal is worth what you pay for it. A good appraisal takes time and time is money. Jewelers who give out this sort of verbal appraisal are doing neither their client nor their profession any good. Courts in some jurisdictions have held that a free appraisal is worth just what you paid for it…nothing! And, by the way if you are a professional you may be “held to it” in a court of law. Jewelers are not the only ones who do this sort of thing, professionals do not always act professionally. May I offer a cautionary tale?

Take me out to the ballpark…

About two months ago I sold an extraordinary 3.30 carat Burma Ruby (pictured) The client, rightly concerned with value, wanted the gem appraised. He asked me if I could recommend and appraiser and aside from the ethical problem of the seller making such a recommendation I had a tough time thinking of anyone other than a wholesale dealer specializing in rubies with experience enough to do it and wholesalers do not know the retail market. To aid the client I obtained an American Gemological Laboratory full quality report. The AGL report graded all aspects of the gem and issued an overall quality grade. I highly recommend this report for important gems. It provides one objective basis to begin the valuing process. (see the report at www.rwwise.com, click gallery, gemstones, ruby)

The client then contacted a professional member of one of the organizations listed above and asked the appraiser for a ballpark estimate and faxed the AGL report to the appraiser. Without ever seeing the gemstone, this appraiser gave the client a “ballpark” price that was so ridiculously low that the client, who had been looking for a ruby for several months realized the price was absurd and decided he needed another appraiser.

How could any professional appraise a gemstone without examining it? You’ve got me! In the case of this so-called professional, he hit a foul ball. Luckily, the client knew more than the appraiser otherwise I might have lost the sale.

The client then asked two well known gemologists, Richard Drucker and Stuart Robertson of Gem World International publisher of The Guide, a wholesale gemstone price guide, to do an appraisal. In a subsequent article in Gem Market News written on appraising this ruby here is what Mssrs. Drucker and Robertson said this stone:

“Pricing this ruby was a challenge…The color was at the top of the spectrum…”

“we looked for comparables…Rubies of this caliber cannot be priced by the cost method and only market data will suffice…”

“…This becomes a gem for the collector’s category and that is an important lesson in pricing. The stone is an example of a gem that grades above The Guide’s extra fine category.”

Gem Market News, Vol. 25, No. 5, September, October 2006, p. 12

Evaluating an ultra-fine gem is difficult because, as Drucker says, you must find comparable stones and if you can’t find comparables you are like a tight rope walker dressed in his underwear balanced on a high wire working without a net. In the end, Drucker & Robertson, after consulting a number of dealers, appraised the stone for substantially more than the client paid and several times the price suggested by Mr.ballpark the professional appraiser.

To sum up, if you want a gem, any gem, appraised. Find a professional with demonstrated familiarity with the gemstone. Check the credentials of local jewelers by checking what they have in their inventory. If they don’t stock the stone, they don’t know the stone. Choose a disinterested professional and pay the price. Don’t expect something for nothing, get a signed document and watch out for foul balls and low inside drives.

Interested in reading more about real life adventures and secrets of the gem trade? Follow me on gem buying adventures in the exotic entrepots of Burma and East Africa. Visit the gem fields of Austrailia and Brazil’s famous Capao mine. 120 photographs including some 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

Only $39.95. You can read a couple of chapters online: www.secretsofthegemtrade.com.

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