November 27, 2001
Gem Labs Scrambling for Answers to USPS Mail Irradiation
The United States Postal Service's plan to irradiate mail at some sorting facilities on the East Coast for anthrax decontamination poses a problem when shipping gemstones through USPS, particularly if irradiation of mail becomes more widespread. USPS is the most widely used method of shipping diamonds and colored gems between dealers, jewelry manufacturers and retailers. Two main aspects are likely to emerge: radiation's effect on color in gems as well as features of radiation damage in subsequent spectroscopic analysis.
Laboratories across the U.S., including those of the Gemological Institute of America, American Gem Trade Association and Adamas Gemological Labs, say they are currently submitting gemstones and diamonds to and conducting tests with commercial irradiation facilities to better understand the before and after effects of electron irradiation of gemstones. Experiments focus on typical mail packages containing gemstones and diamonds, which are irradiated at the doses necessary to kill anthrax spores. GIA's findings will be reported later this week.
Experts say only a few gems could have their color affected by the doses of irradiation used by USPS quartz, fluorite and some glasses appear to be the most susceptible. Significant color alteration, such as seen in topaz, reportedly requires much higher doses than USPS is using. Color alterations depend on the type and content of mineral impurities within the gems, as well as the dosage of irradiation they are exposed to. Experts on irradiation say the amount of electron irradiation USPS is using is too low to cause long-term radioactivity in gemstones, and should not pose a health hazard.
While many gems and diamonds would not necessarily suffer color alteration with the proposed doses, Marty Haske of Adamas Gemological Laboratories, Brookline, MA, says advanced spectroscopy would indicate in most cases that irradiation took place. This is of enormous concern with high-value gems such as colored diamonds, where natural colors are valued in exponentially higher dollar amounts than their irradiated counterparts.
- by Robert Weldon, G.G.