IGI issues alert about CVD synthetic diamonds being submitted to the lab

In its recent trade alert for the global gemological community, the International Gemological Institute (IGI) has informed that its laboratories in Antwerp and Mumbai have received a few hundreds of CVD synthetic diamonds with the clear aim to have these man-made diamonds certified as natural diamonds, in the past few weeks.

IGI readily identified these as synthetic diamonds. The laboratory described that in each case the synthetics had very similar characteristics and may therefore have had a common origin.

The CVD synthetics submitted in unusually large numbers were as follows:

Mostly F to J Color, Clarity VVS – VS - Internal characteristics were feathers, pinpoints, small dark crystals. The inclusions are strikingly similar to natural inclusions, hence, microscopic observation is insufficient to conclude.

Sizes - ranged from 0.30 ct to 0.70 ct.

Polish, Symmetry and Cut -either “Excellent” or “Very Good”.

Bruted or faceted girdles.

Absence of any laser inscription.

They were all type IIa and were referred as such by DiamondSure.

All synthetics when tested with DiamondPlus, gave “refer CVD” result. Upon being viewed in DiamondView the synthetics showed bluish green fluorescence and blue phosphorescence, with characteristic striations. Also, they showed moderately strong photoluminescence from H3 and nitrogen-vacancy optical centres (zero-phonon lines at 503 nm and 575/637 nm respectively) and exhibited photoluminescence at 737 nm that is attributed to silicon-vacancy centres.

The lab suspects that the volumes of colorless synthetic diamonds being released on the global markets is increasing , and may perhaps already be prevalent throughout the diamond centres. As such, IGI management decided to liaise and consult with the Belgian Federation of Diamond Bourses (BFDB), DTC Research, and the AWDC. The lab also decided to share detailed scientific information with other gemological laboratories around the world. Trading in misrepresented or undisclosed products, whether inadvertently or not, could cause irreparable damage to the industry’s reputation and undermine the integrity of the diamond supply chain, damaging both trade and consumer confidence.

As such, the lab believes that the recent events call for having ready access to methods for detecting synthetics. Parcels of stones containing unusually high proportions of type IIa’s should be treated with particular caution. CVD synthetic diamonds are undetectable when using only traditional diamantaires’ tools such as loupes and microscopes. Therefore, gemologists’ expertise is of paramount importance. Also, according to IGI, in most cases of the synthetics submitted to the lab, they were purchased at prices that were equivalent to prices of natural diamonds.