NY lab reports finding more undisclosed synthetics

New York--The Analytical Gemology & Jewelry Laboratory (AG&J), the same lab that reported the discovery of a parcel of 243 undisclosed lab-grown yellow melee diamonds, is warning the industry that it recently found synthetic brown melee mixed in a batch submitted as natural.

The New York-based laboratory said Friday that the stones were grown using the chemical vapor deposition process (CVD) but were sold as natural brown type IIa diamonds.

The lab said at the end of July, it graded a batch of 18 diamonds, 17 rounds and one marquise cut, totaling 16 carats and ranging in size from 0.14-0.635 mm, with color ranging from F to gray and clarity of VVS to SI. The diamonds purportedly were mined, HPHT-treated diamonds.

Using its proprietary testing system, which can test melee, AG&J found that 13 of the 18 stones, or 72 percent, were actually CVD-grown diamonds.

An American gem dealer who specializes in HPHT-treated diamonds submitted the stones after purchasing what he believed were mined diamonds from a trade source with whom he had a long-standing relationship, the lab said.

The dealer bought the stones in question on the open market in Mumbai as type IIa brown diamonds. The dealer used a portable FTIR instrument to test the stones to ensure they were type IIa or very low nitrogen stones that could be HPHT treated.

The client became suspicious when some of the diamonds turned gray during the HPHT treatment and none of the stones achieved a color grade higher than I.

AG&J said testing revealed the CVD diamonds were produced using different parameters and reactors, which means they came from different factories.

“It was not surprising that the client could not detect the CVD diamonds using FTIR spectroscopy, as this requires more sophisticated methods that also have to keep up with the changes in the production of CVD- and HPHT-grown stones as well as treatments,” said AG&J CEO Dusan Simic.

He added that the discovery of these stones shows that the production of CVD-grown diamonds has become so cheap that they are beginning to penetrate the low end of the market.

The failure of companies to disclose the submission of lab-grown diamonds has increased in tandem with the stones’ presence in the industry, which comes as no surprise to the leaders of the world’s largest gem-grading laboratories.

As Jerry Ehrenwald, president and CEO of IGI North