GIA Impostor Alert: CVD Rough Made to Mimic Natural Diamond

(IDEX Online) - A rough diamond submitted to the Gemological Institute of America (GIA) turned out to be a CVD lab grown that had been deliberately cut to look like a natural stone.

The 6.87-carat near-colorless crystal closely resembled a natural rough octahedron, say the authors of an article in the latest issue of Gems & Gemology.

But advanced laser testing - Raman spectroscopy - confirmed its true origin.

The authors say it's the first instance, to their knowledge, of a CVD lab grown being deliberately fashioned into the approximate shape of a rough natural diamond crystal.

They concluded that the only motivation for producing such a stone from CVD material was as a deliberate attempt at deceit.

Producing a stone like this from a block of lab grown (CVD) diamond is not straightforward, they said.

Cutting a finished gem from such a block while working with that specific crystal structure would be difficult and wasteful, and would yield a polished stone significantly smaller than one cut directly from the as‑grown block.

The stone was not, in fact, a true octahedron. Only one pair of opposite faces was parallel, and none matched the planes typical of natural diamond crystals.

"Should synthetic diamonds fashioned in this way become more prevalent, an immediate screening solution for rough diamonds could be implemented," the authors say through adaptation of existing screening instruments for polished diamonds.

Pic courtesy GIA.