GIA close to solving mystery color treatment

Rob Bates

The Gemological Institute of America is close to figuring out the mystery treatment that may have temporarily improved the color of some 500 diamonds, GIA president and CEO Susan Jacques said at the annual Rapaport conference on grading standards on May 31.

We know what is being done, but we don’t know how it is being done,” added Phil Yantzer, vice president of GIA’s Carlsbad lab services, noting that most — but not all — of the diamonds involved were “off-color.” But since off-color stones are more common, that didn’t raise a red flag.

He declined comment on one questioner’s contention that it must be a coating, saying that GIA graders regularly check for coatings.

On the subject of grading, most of the labs on the panel said they adhere to the GIA standard but agreed that consumers don’t realize that not all labs grade diamonds the same way.

Moderator Saville Stern relayed that an attorney put up a site asking consumers who have had their diamonds graded by a lab other than GIA to join a class-action suit.
“If we allow labs to follow their own standards, and call something a D when it is a K, we are going to bring the downfall of our industry,” Stern said. “The question is what do we do with labs that don’t follow the standards.”

One audience member suggested that the industry might need some kind of external body that monitors standards among labs, though labs on the panel expressed less enthusiasm for that idea.

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