Version 2.0 of the NDC’s ‘Assure’ Directory Is Now Live
Assure is the program the Natural Diamond Council launched in 2019 to test lab-grown diamond screening devices.

Assure is the program NDC launched in 2019 to test and analyze the performance of as many diamond verification instruments—devices designed to tell the difference between natural and lab-grown diamonds, as well as diamond simulants—on the market as possible.
Underwriters Laboratories (UL) in Canton, Massachusetts, and the University of Antwerp in Belgium perform the testing.
NDC said this second round of the program and its updated directory show the results of testing the machines on an updated sample of natural diamonds, lab-grown diamonds, and diamond simulants in a range of sizes.
The sample is curated to reflect goods currently in the market, as well as “individual stones that anticipate future trends and pose some of the greatest challenges,” NDC said.
“It would be no good to test these machines using synthetic stones that are known to be easier to identify,” explained Grant Mobley, NDC’s jewelry and watch editor. “We need to make sure these machines work under the most difficult scenarios possible with the most difficult-to-identify stones as possible, as well as the most common types of synthetics on the market.
“In order to do this, we work with gem labs to secure the most common types of stones as well as stones they have identified as more difficult to identify. These more difficult stones are usually very rare on the market, some developed specifically to try to ‘fool’ the machines, but we want to make sure the machines can test them regardless.”
The second version of the program also tests diamonds already set into jewelry, whether in an open- or closed-back mounting.
Currently, there are only three lab-grown diamond screening devices listed in the Assure 2.0 directory: De Beers Group’s DiamondSure and SynthDetect, and M-Screen Ultra from HRD Antwerp.
Mobley said “many more” will be added in the coming weeks as manufacturers submit their newest machines to test.
He also noted the Assure program is ongoing, so as new machines come to market, NDC will work with the manufacturer to try to get them in for testing.
NDC said this updated version of the online directory has improved search filters to allow users to more easily find instruments based on their needs: types of diamonds used, volumes of diamonds processed, size of device, level of expertise required, etc.
The new portal also provides more details on the Assure 2.0 program as well as information on how to protect the integrity of the diamond pipeline.
Previously published test results will still be available via the Assure 1.0 directory.
Manufacturers of diamond verification instruments can now submit to the program both new and existing instruments whose Assure verification is about to expire. (Companies that submit machines for testing receive an “Assure Tested” sticker to place on their instruments. The results, and the sticker, are good for two years. After that, the machine must be resubmitted for testing to still claim to be “Assure Tested.”)
For more information or questions, email assure@naturaldiamonds.com.
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