HRD Antwerp recently examined a 3.09-carat CVD lab-grown diamond. It was the first time that a CVD synthetic diamond of such a size was seen at the lab. CVD (Chemical Vapour Deposition) is a technique where diamonds are grown in a specially developed growing chamber using a carbon rich gas.
Both D-screen and Alpha Diamond Analyzer, two screening instruments developed by HRD Antwerp to distinguish possible lab-grown or HPHT treated diamonds from natural diamonds, indicated that the stone needed further testing. Alpha Diamond Analyzer confirmed that the stone was a Type IIa diamond and therefore potentially lab-grown or HPHT treated.