Lab Finds New Batch of Undisclosed Synthetics

The Analytical Gemology & Jewelry lab said it recently took in a batch of diamonds, later determined to be synthetic, that had not been identified as such.

AG&J said the parcel, purchased on the Mumbai open market in July, consisted of 18 diamonds (17 rounds and one marquise), weighing a total of 6 carats, ranging in size from 0.14-0.635mm, with colors ranging from F to Grey, and clarities from VVS to SI. The New York City-based lab determined that 13 of the diamonds were synthetic, produced with the CVD method, and then treated with HPHT. 

The buyer, who specializes in HPHT-treating natural stones, had used a portable FITR spectroscopy device to determine whether the stones were type IIa or Ia. However, the device did not detect the gems were synthetic—demonstrating that advanced technologies are increasingly needed to spot man-made stones, AG&J CEO Dusan Simic, tells JCK.

The incident also shows that diamond-growing technologies are getting less expensive, and are starting to penetrate the low-end of the market, Simic says.

“They can clearly growing them faster than before, and the price is going down,” he says.

Simic does not believe the stones originated from lab-grown diamond producer Gemesis. In fact, his testing indicates they were produced from different factories, which also seems to show a greater number of facilities are now producing lab-grown stones.

JCK News Director