GIA is not the only lab reporting an increase in undisclosed lab-grown diamonds. From the newsletter of GGTL Laboratories:

GGTL Laboratories has finally found the very first undeclared melee-sized colorless CVD synthetic diamond in a parcel of around 6,000 natural diamonds that have been purchased in India. This diamond was found during the Diamond Show in Basel, where we were exhibiting with our DFI Mid-UV Laser+ fluorescence system.

This tiny (1.6 mm diameter) CVD synthetic diamond was graded F color, had no inclusions at 10x, and hence was graded IF clarity. 

“The stone was completely undeclared in the parcel,” lab director Thomas Hainschwang tells me. “The client who tests a lot of his material did not have the slightest idea that there was a synthetic in his parcel. Initially, he did not even want to believe it.”

He adds: “It is the highest-grade stone we have seen so far, but this certainly relates to the small size. If this were larger in size it would obviously be lower in color.”

The lab cautions that it found this one stone out of a parcel out of 6,000 and out of countless stones it’s looked at. It also recently discovered a melee-sized vivid yellow in a parcel from Hong Kong.

So for the time being, as GIA also says, every indication is that these stones still comprise a small percentage of the overall industry.

The point is not that the industry should panic. But it’s important to realize that lab-grown diamonds are out there and not always disclosed for what they are. It will become more and more important to buy only from people you trust and test stones and parcels of which you are unsure. If you find an offer that looks too good to be true, it just might be.

Rob Bates

JCK News Director