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DPA Grades Scanners for Synthetic Melee

The project by the Diamond Producers Association (DPA) testing lab-grown detectors has expanded to melee, a segment of the market highly prone to undisclosed synthetics.

The Assure program reviewed 12 machines using a sample of 1,000 mined diamonds and 200 synthetics, as well as 200 diamond simulants. The stones ranged in size from 0.005 to 0.02 carats, with D to J color.

Six instruments achieved a “diamond false-positive rate” of 0%, meaning they didn’t mislabel any lab-grown stones as natural. The others received scores ranging from 0.3% to 9.4%, representing the percentage of stones they wrongly classified as being from the earth.

Mixing of natural and synthetic diamonds has been a major threat to the melee sector in recent years. Last year, the Gemological Institute of America (GIA) received a batch of more than 1,000 tiny stones that contained only one natural diamond, noting there had been an “exponential” increase in the volume of synthetic melee — both disclosed and undisclosed — customers sent for identification since 2016.

The overall performance in the latest DPA analysis for checking melee was roughly on a par with tests the Assure program carried out using a core sample of larger natural diamonds, synthetics and simulants. In those tests, 10 out of 16 detectors scored the ideal 0% when scanning the stones, which ranged from 0.02 to 0.20 carats. The Assure project initially tested 11 scanners against that sample earlier this year, and recently added a further five machines.

Out of the total of 16, four instruments were not tested on melee because they do not claim to work with stones of that size.

The DPA and Signet Jewellers have partnered on the program, with third-party testing agency UL carrying out the assessments. The DPA released the initial 11 performance reports on its online Assure directory in March, and published the additional five results to coincide with the start of the JCK Las Vegas show in late May and early June.

UL also retested the GIA iD100 machine, after the Assure steering committee approved the manufacturer’s request to provide additional training and guidance to the technician carrying out the procedure.

The scores show machines’ performances in a range of criteria, including the ability to state conclusively whether a diamond is natural or synthetic, rather than referring the stone for further testing.

“We are positively encouraged by feedback that manufacturers are taking learnings from the Assure program into their research-and-development efforts to further excel the performance of their instruments,” Lisa Levinson, strategic project manager at the DPA, told Rapaport News in an email Monday.

A handful of additional machines are currently going through testing, with the DPA planning to release the results when they become available.

Courtesy - Rapaport News

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