A synthetics detector costing less than $7,000 is one of only three machines that conclusively identified 100% of lab-grown diamonds in a recent industry-wide study.

Yehuda’s Sherlock Holmes, priced at $6,495, correctly spotted all synthetic diamonds in a “deliberately challenging” sample, according to a report the Diamond Producers Association (DPA) and Signet Jewelers released Tuesday. 

De Beers’ DiamondView, which costs $35,000, also scored full marks. So did Presidium’s Synthetic Diamond Screener II, which sells for $599, but that machine also had a 15.5% false-positive rate. (Clarification: The Synthetic Diamond Screener II works by screening out type IIa colorless diamonds, as those are likely to be synthetic, rather than actually identifying lab-growns.) DiamondView didn’t mislabel any synthetics as natural, while Sherlock Holmes was wrong for 2.5% of mined stones. 

Two other De Beers products, SYNTHdetect ($17,000) and DiamondSure ($18,200), accurately referred all lab-growns for further testing, as did the Gemological Institute of America’s (GIA) iD100 ($4,995) and HRD Antwerp’s M-Screen+ ($63,000). Those machines are designed to refer synthetics rather than detect them conclusively, according to the study, known as the Assure Program.

The DPA and Signet tested the ability of 18 scanners from 11 manufacturers to identify natural diamonds, synthetics and simulants from a mixed batch, the two organizations said. They assessed the machines’ performances against a standard developed by UL, a third-party testing agency, as well as a technical committee comprising scientists and academics from gemological institutions, including the GIA and De Beers’ International Institute of Diamond Grading & Research. Testing took place at UL’s laboratories in Canton, Massachusetts.

The wide-ranging research looked at how well each contraption detected or referred man-made stones, including the rate at which they gave false positives. The DPA has published the full results in a directory on its website.

The directory also lists key characteristics of the machines, such as whether they work automatically or manually or require an expert operator, as well as the speed at which they process stones, which varies significantly.

For instance, DiamondView and Sherlock Holmes require expert operators, while a novice can use Synthetic Diamond Screener II. Not all the machines in the test work on mounted jewelry, and one of them, Taidiam Technology’s DiamondDect 5, only looks for High Pressure-High Temperature (HPHT) goods.  
“Through the Assure Program, we will support the diamond trade, from independent jewelry retailers to large diamond manufacturers, to make informed decisions on how to ensure that undisclosed laboratory-grown diamonds do not enter their natural-diamond supply chain,” said DPA CEO Jean-Marc Lieberherr. 

The Assure program will update its directory as manufacturers submit new instruments, it said.

Clarification, March 6, 2019: This article was updated to clarify the methods and results of the test.

Image: A selection of detection machines that underwent testing. (Diamond Producers Association)

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