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GIA Spots Treatment Fraud with 6ct. Polished

May 30, 2018 10:35 AM   By Rapaport News
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RAPAPORT... The Gemological Institute of America (GIA) has uncovered a treated diamond carrying a false inscription that fraudsters had apparently created to make the stone appear untreated.

Swindlers appear to have carefully selected a grading report for an untreated diamond with extremely similar characteristics to their treated stone, and created a fake GIA laser imprint on the treated stone’s girdle, according to a grader’s lab note.

The organization’s Hong Kong laboratory received the round brilliant, 6.30-carat, F-color, internally flawless natural diamond for verification of its grade, Billie Law, who works at the GIA in Hong Kong, wrote in the spring 2018 issue of the institute’s journal, Gems & Gemology.

Scientists found the polished stone’s characteristics were inconsistent with a report the GIA had issued a few months earlier for a diamond with an identical code on its girdle. That number referred to a fractionally smaller diamond — 6.30216 carats, in contrast with the 6.30402-carat stone in front of them — with F color but VVS1 clarity.

The other difference was that the stone the gemologists had in their hands was clearly treated using High Pressure-High Temperature (HPHT), a common method for improving a diamond’s color. The scientists checked this using spectroscopic testing that easily revealed the stone’s true nature, Law wrote.

“This case should raise awareness among the industry and the public that, although rarely encountered in larger stones, this kind of fraud does exist,” the grader continued. “Verification services at GIA confirm that an item is exactly the same as the one described on a previous report and has not been recut or treated — or, as in this case, replaced with a similar-looking stone.”

Grading laboratories have discovered several such cases in recent years, though usually involving smaller stones. In 2017, the GIA identified a girdle inscription on a 1.76-carat synthetic diamond to be a forgery created by fraudsters trying to pass it off as a natural stone. Last month, China’s National Gemstone Testing Center said it had received a 3.10-carat synthetic-diamond ring carrying a fake report and inscription that falsely presented it as natural.

Images: Tony Leung and Billie Law 
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Tags: Billie Law, diamond grading, fraud, Gemological Institute of America, GIA, grading, Grading labs, Hong Kong, HPHT, HPHT treatment, Laboratories, Labs, Rapaport News, treated diamonds, treatment
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