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01/05/2015

Heat-treatment of spinel

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Authors: Adolf Peretti, Ngwe Lin Tun, Thomas Armbruster
Published in: Contributions to Gemmology No. 11

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11/10/2015

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GRS Newsletter

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GRS Gemresearch Swisslab

4 days ago

Dear customers,

GRS has recently posted some updated research on sapphires that have undergone Pressure High Temperature (“PHT”) treatment (see GRS website). GRS had disclosed this type of treatment since mid 2015 to a total of 73 different customers and issued hundreds of reports.

Earlier this year in our New York lab, we discovered that these PHT treated sapphires were traded in the market without proper disclosure, and the reports issued by other laboratories on these sapphires did not detect this type of treatment. This raised some questions within the New York gemstone community resulting in stones being returned back to the supplier and ultimately to the producer (the treatment is done in Korea and can be marketed from anywhere in the world).

In response, the producer approached GRS and demanded that the treatment be classified as “H - conventional heat” only in our reports. As a promise to the producer and re-confirmation of our policy, GRS updated our research on an additional 140 samples and re-confirmed our previous decision from 2015 to separate the disclosure of PHT treatment from conventional heat treated sapphires.

GRS customers can be assured that GRS maintains our stance on the disclosure of this treatment since mid 2015 (formerly as “HPHT” and now as “PHT”). No re-checks are required.

GRS does not support LMHC’s (CGL, CISGEM, DSEF, GIA, GIT, Guebelin Gem Lab and SSEF) recent decision to take on a policy of non-disclosure on this subject.

Nevertheless, we are very pleased that our research was very well received by a wide range of trade members and organizations, and that our initiative to enhance disclosure of this new type of treatment has contributed to a more transparent market.

Yours sincerely,
Dr. A. Peretti

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