Gemological Science International (GSI) has warned the trade to be cautious and thorough while identifying lab-grown diamonds, stating that gemmologists at its Mumbai lab recently came across a HPHT diamond with what appeared to be a laser-drilled channel normally seen only in treated natural stones.

Emphasising that it is a misconception that a diamond can be identified as natural or lab-grown based on inclusions, the lab pointed out that in the case cited above that an inaccurate conclusion could have been reached by classifying the diamond as natural, based entirely on the laser drill channel, a treatment hitherto seen only in natural stones.

The lab said GSI researchers and scientists observed and studied this diamond since it would be highly unusual to laser drill a lab-grown diamond. Upon closer examination, the “laser drill channel” was found to be a typical HTHP inclusion that was cut open from top and pavilion. After this, the content of the inclusion was acid bleached out, while some residue was still present. The remnants of the inclusion have a strong resemblance to a laser drill treatment – this treatment is generally used to “clean out” black inclusions and enhance the appearance of a diamond.

The lab said that “there are no recorded cases of lab-grown diamonds with this treatment, nor would it currently make sense to laser drill these diamonds”.

“Diamond growing technology continues to improve and growers are trying to mimic natural diamonds in every possible way,” said, Nick Del Re, GSI’s Chief Information Officer.

The lab said it was important to use proper processes, equipment, and expertise when identifying diamonds and added that its research department continues to conduct advanced testing on lab-grown and identification.

Pic caption: The HPHT diamond with what appears to be a laser-drilled channel

Pic courtesy: GSI