Previously telling natural rough diamonds from lab grown rough diamonds was fairly straightforward due to the typical cubo-octahedral shape seen with diamonds produced by HPHT (High Pressure High Temperature) and the characteristic plate structure of diamonds produced by CVD (Chemical Vapour Deposition) which significantly differs from the morphology of natural diamonds.
However some caution is required as recently HRD Antwerp came across (near-) colourless lab grown diamonds featuring octahedral and other “natural” shapes. The fact that rough lab grown diamonds featuring a morphology previously unique to natural diamonds are now entering the market, makes it more difficult for less experienced rough traders to make a visual on the spot identification of lab grown rough diamonds.
The rough melee goods examined by HRD Antwerp varied in size from 0.01 ct to 0.04 ct and were produced by Taidiam, a Chinese company offering both HPHT and CVD lab grown diamonds.
“A more in-depth investigation on a microscopic level however still reveals the remnants of a seed crystal used to position the precipitated carbon atoms, and / or other characteristics inherent to lab grown diamonds. An infrared spectroscopy analyses by our research team has also demonstrated that all colourless diamonds included in the examination were found to be type IIa or type IIb” explains Dr Katrien De Corte, Chief Education Officer HRD Antwerp.
“The fact that lab grown diamonds now also occur in an octahedral shape merely affects the rough trade as once the diamonds are polished, dedicated equipment still provides a full proof solution for identifying lab grown diamonds in our lab” Mrs De Corte continues.
It's HRD Antwerp’s mission to conduct advanced on-going examinations of both rough and polished goods in order to help diamond professionals cope with the challenges rapidly evolving scientific and technological developments may hold.