AG&J Identifies Synthetics Melee Mixed with Natural Diamonds

New York-based gemological lab, AG&J, recently received a large batch of allegedly natural diamond melee, however,  testing revealed that more than 5 percent of the batch was synthetic diamonds.
The client who submitted the diamonds claims the lot was purchased from a well-known trade source, with whom he had a long-standing business relationship. He had no idea synthetics were mixed in the lot.
With permission from their client, AG&J reports that a batch consisting of 4,566 round, full-cut diamonds weighing a total of 56 carats, ranging in size from 0.7-2.5mm, color ranging from fancy intense to vivid yellow with some brownish modifier, and a clarity range from VS to SI, was submitted to the lab at the end of December 2012.
Using their proprietary melee testing system, which analyzes each individual diamond, and not just a sampling, AG&J identified 243-HPHT grown synthetic diamonds. The remaining batch was natural and untreated.
Dusan Simic, the CEO of AG&J, believed that the data collected points to all the synthetic diamonds coming from one source, created to purposefully commit fraud.
“It was surprising that only four of the 243 synthetic diamonds showed weak magnetic properties, which are the results of metallic inclusions,” said Simic. “In my opinion, this indicates that the synthetic stones were not mixed into the batch accidentally. Non-magnetic diamonds were chosen on purpose because checking for magnetism is one of the quick, low-tech ways to screen melee for synthetics.”
The recent findings confirm the necessity in checking melee diamonds for synthetics, treatments and imitations. Simic stated, “It is crucial to check every single stone within a batch. Random screening is not enough. If the end consumer is purchasing jewelry with synthetic diamonds, believing they are natural, then the trade has not done its due diligence in ensuring the proper identity of diamonds traded and sold. Both our ethical obligation and reputation is in question if diamond melee is not screened.”
The AG&J (Analytical Gemology & Jewelry) Laboratory specializes in the identification of diamonds and their treatments. Seasoned in research and development, the lab concentrates on finding new identification procedures and consulting in HPHT and APHT treatment and technology. Responding to the trade’s concern of rapidly growing occurrences of synthetic and treated diamonds mixed in natural batches, and in mounted jewelry, AG&J developed a system for batch testing melee accurately in a cost-effective way. The system is based on internationally accepted diamond identification methods, such as: Raman spectroscopy, absorbance measurement in the UV-VIS-NIR range, and FTIR and photoluminescence.
AG&J provides melee-testing services, starting at $2 per stone. To further address this growing issue, the lab is currently developing a system to identify stones mounted in jewelry. “We hope to have the first prototype of this system working by mid-2013,” said Simic.

Source: diamonds.net