GIA Uncovers Natural Diamond with Synthetic 'Overgrowth'

The Gemological Institute of America (GIA) has uncovered a natural diamond with a blue synthetic coating, and has warned that other ‘hybrids’ might be on the market.

A GIA industry announcement confirmed the natural-synthetic composite was submitted to the New York laboratory as a natural fancy 0.33-carat blue diamond.

It added that the stone was the first of its kind the organisation had encountered.

According to reports, a number of unusual characteristics gave away the diamond’s synthetic nature. Firstly, the stone contained both nitrogen and boron defects, described as a ‘rare combination’.

It was also found that the diamond was a mixed Type Ia and IIb, another uncommon property.

In addition, the GIA announcement noted the diamond’s silicon deficiency defects (sIv). Although sIv can be observed in a natural diamond, the combination of the stone’s sharp boundaries, fluorescence, phosphorescence and sIV suggested the top layer was a chemical vapour deposition (CVD) synthetic.

While the synthetic layer was only 80 microns (0.08 millimetres) thick, it was enough for the diamond to be graded as a fancy blue.

The GIA industry notice, authored by GIA director of research and development Wuyi Wang and New York GIA researchers Kyaw Soe Moe, Paul Johnson and Ulrika D’Haenens-Johansson, also stated there were likely to be more undiscovered cases in the industry.

“Identification of colored diamonds should be performed very carefully by looking for unusual characteristics, such as a straight boundary line associated with an interface plane, and fluorescence zones with sharp edges in DiamondView images,” it read. “Examination of this fancy-coloured composite diamond indicated that similar challenges could exist for colourless and near-colourless diamonds.”

De Beers rolls out synthetic course

In other synthetic diamond news, De Beers Group’s International Institute of Diamond Grading and Research (IIDGR) will initiate a series of educational courses on how to identify synthetic diamonds.

The two-day Synthetic Diamond Detection course will aim to provide participants with the knowledge to distinguish synthetic diamonds from natural, rough or polished stones using a range of techniques and instrumentation.

This training program will take place in India from 15 May to 16 May and the US from 8 June to 9 June. The course will then be delivered more widely through a ‘mobile lab’.

“The mobile lab is a portable ‘lab’, which allows IIDGR to physically bring key instruments and materials to each course, meaning the course can be held at almost any location,” IIDGR director of education Jodine Perrin explained to Jeweller.

According to IIDGR president Jonathan Kendall, the ability to detect undisclosed synthetic stones was becoming increasingly important for diamond traders and retailers.

“The introduction of the course represents another key step towards the IIDGR’s mission to ensure industry and consumer confidence in the integrity and quality of diamond purchases,” Kendall said.

Perrin also stated that a polished-diamond grading and diamond foundation course would be offered.

The De Beers Group established the IIDGR in 2008. Based in London, Antwerp and Surat, the IIDGR offers a range of diamond grading services and equipment.