More undisclosed lab-grown diamonds have shown up at a lab—this time the GIA lab in Hong Kong in June.

The 10 stones were swiftly identified as lab-created, the Institute said.

The incident was announced in the Gems & Gemology monthly eBrief.

The news comes on the heels of the International Gemological Institute’s May alert that 600 synthetic colorless diamonds were submitted to the International Gemological Institute without disclosure. One report traced the stones to a New York company.

The stones were comparable in quality to naturals, the Institute says, noting they were round brilliants, ranging from 0.30 to 0.35 ct., with F–H color grades, and clarity grades ranging from VVS1 to VVS2, though one sample received a VS1.  

As with the Antwerp parcel, the stones were described as “similar” to those produced by manufacturer Gemesis, as they were both CVD-grown and then treated with HPHT afterwards.

JCK