How to Choose a Colored Gem Lab

Colored gemstones are sent to laboratories to determine their authenticity, verify their country of origin, or identify treatments. Deciding which laboratory to use depends on what you need to know. Services and philosophies differ from one lab to the next. Here are some factors to consider when you make that choice.

Choosing a laboratory for colored gemstones can be confusing. For color, the choices are tougher than with diamonds because the labs differ greatly in what they offer and how they report the results. With diamonds, price and turnaround time are the key issues for many jewelers (JCK, September 1999, p. 122). With color, the type of information required is far more important than time or money.

Authentication. The sophisticated new synthetic gemstones found on the market today make some gems difficult to authenticate. It’s therefore quite appropriate for a gemologist to obtain a second, authoritative opinion. The standard gemological laboratory has equipment worth perhaps $20,000. The highly regarded gem labs, whose instruments easily exceed $250,000, can perform higher levels of testing.

All the major laboratories will identify gemstones as natural or synthetic. While magnification is still a primary identification feature, labs also use other sophisticated equipment. The Gemological Institute of America’s Gem Trade Lab has instruments for X-radiography, energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectra analysis, imaging spectroscopy, and Raman laser spectroscopy, among other analyses. Does your store have these? Probably not, which is why a lab of higher authority is often consulted.

Even the major labs sometimes struggle with identification calls. A prime example is alexandrite. A new synthetic alexandrite reportedly is difficult to distinguish from the natural. Because of the dollars at stake, a second opinion may be justified. One prominent lab even admitted sending one specimen to the GIA lab for another opinion. There’s nothing wrong with that. Communication between labs is good for the entire industry. Each gemological challenge for the jeweler or the laboratory results in further education that will help when the next gem comes in for analysis. Remember, too, that in rare occasions even the best-equipped gem lab may end up with inconclusive test results.

Synthetic amethyst likewise is a continuing problem in the industry. Labs used to try to determine how the amethyst was grown. Technicians initially used a test for “twinning” until synthetic growers learned how to grow twinned crystals. Now the test is no longer useful. GIA and the American Gem Trade Association have a new test but haven’t revealed how it works. Unfortunately, because of the low cost of amethyst and the high cost of identification, few jewelers are using this test. Large manufacturers may test samples, but not all gems are being tested. Since up to half of all amethysts are thought to be synthetic, we can only hope that more testing will be done.

B-jade and C-jade also pose a problem for the industry. B-jade is polymer-impregnated jade, while C-jade is impregnated and dyed. The cost of these materials is much lower than that of untreated jade. Yet few laboratories have the necessary equipment to identify B- or C-jade. Mason- Kay Co. in Denver, a major seller of jade, considered the impregnated jade issue so important that the company purchased equipment to identify it. Mason-Kay now tests all its jade and offers the service (for a fee) to the trade.

The European Gemological Laboratory-USA is using new proprietary techniques for pearl analysis. Older methods involved chemical immersion and X-ray film photography. The new equipment eliminates the need for both, according to EGL’s marketing director, Gregory Sherman. Laboratory investigators get an instant image on screen and can measure the nacre thickness instantly.

Country of origin. The second area of need is country-of-origin reporting. Not all labs generate origin reports. (GIA, for example, does not). However, when origin reports are included with important gems, the value of the gem may double, depending on the rarity of the origin. For example, Burma rubies may sell for twice the price of similar rubies from other places.

The American Gemological Laboratories in New York is known for country-of-origin reporting. Auction houses often sell gemstones with origin reports from AGL. AGL is not the only lab issuing these reports. The Gübelin laboratory in Geneva and the Swiss Gemmological Institute (SSEF) in Basel also do origin analysis. Both are well-respected, and they too are used by auction houses worldwide. The AGTA laboratory in New York now offers origin reports as well.

The basic method used to determine origin is inclusion study. While GIA does not do country-of-origin reporting, it has amassed a large database of information and could conceivably get into this area at some point.

Country-of-origin reporting is not without controversy. Occasionally a gem that is submitted to multiple labs may receive different origin reports. There is a degree of subjectivity involved. This is a science that may never achieve total accuracy. As one dealer said, “Geology knows no borders.” Certain characteristics in a gemstone can conceivably be found crossing borders into other countries.

Treatments and enhancements. The third area of need concerns gemstone treatments and enhancements. Labs differ greatly in their views of gemstone enhancements, how they determine enhancements, and how they report the level of treatment. While lab officials talk about the need for standardization, they still offer distinctly different reports.

The greatest disagreement comes with emeralds. Some labs indicate the type of treatment in the emerald (oil, resin, etc.), while others, such as GIA, indicate simply that an enhancement exists. Some labs note the amount of enhancement present, but there’s no standard scale. There are some labs that indicate both the type and level of treatment, while others report only on one of these. In short, there are no set standards for labs in our industry to follow. Thus, when it comes to treatments, it’s no surprise that lab reports can vary greatly.

Richard B. Drucker, G.G., is the president of Gemworld International and publisher of The Guide, a pricing periodical he began in 1982. An international gemstone consultant, he has published numerous books on the jewelry industry.

Major Colored Gem Laboratories

Below is a selective list of major colored stone laboratories and a brief description of their gemological services. Prices for services are too complex to list here because the services offered vary from one lab to the next. Contact the labs directly for a list of their fees.

• American Gemological Laboratories (AGL); 580 Fifth Ave., Suite 706, New York, NY 10036; (212) 704-0727, fax (212) 764-7614; C.R. “Cap” Beesley, president

Services include gemstone identification, grading, country-of-origin determination, and enhancement identification (type and quantity). AGL also offers appraisal services on important pieces through a separate division of the company.

• American Gem Trade Association Gemological Testing Center (AGTA); 18 E. 48th St., Suite 1002, New York, NY 10017; (212) 752-1717, fax (212) 750-0930; Ken Scarratt, director

Services include gemstone identification, country-of-origin determination, and enhancement identification (type and quantity).

• European Gemological Laboratory (EGL USA); 30 W. 47th St., New York, NY 10036; (212) 730-7380, fax (212) 730-7453; Mark Gershburg, manager

Services include colored stone identification, enhancement reports, pearl analysis and identification, and appraisals through a separate division of the company.

• Gemological Institute of America Gem Trade Labs (GIA GTL); (1) 580 Fifth Ave., New York, NY 10036; (212) 221-5858, fax (212) 997-7661; Tom Yonelunas, CEO; (2) Robert Mouawad Campus, 5355 Armada Dr., Suite 200, Carlsbad, CA 92008; (800) 421-7250, fax (619) 603-1814; Sally Ehmke, director

Services offered include gemstone identification and enhancement identification.

• Gübelin Gemmological Laboratory; Maihofstrasse 102; Ch-6000 Lucerne 9; Switzerland; Phone (41 61) 262-0640

Services include gemstone identification, grading, country-of-origin determination, and gemstone enhancement identification (type and quantity).

• International Gemmological Institute (IGI); 575 Fifth Ave., New York, NY 10017; (212) 753-7100, fax (212) 753-7759; Jerry Ehrenwald, owner

Services include gemstone identification, country-of-origin determination, and appraisals.

• Swiss Gemmological Institute (SSEF); Falknerstrasse 9; CH – 4001; Basel, Switzerland; (41 61) 262 0640; Dr. Henry A. Hanni, director

Services include gemstone identification, country-of-origin determination, and enhancement identification (type and quantity). SSEF has compiled a comprehensive book titled Standards & Applications for Diamond Report, Gemstone Report, Test Report. Although the book promotes SSEF’s laboratory services, the reference information is valuable to all jewelers. The 120-page book sells for $65.

Log Out

Are you sure you want to log out?

CancelLog out