Identification

It was stated that annealing can convert typically brown synthetically made (CVD) diamonds into colorless diamonds, and that after having sent these diamonds for diamond jewelry identification, they were not identified as different from natural diamonds.[73] Such claims are often made for new synthetics, simulants, and treated stones, so it is important to validate how the stones were submitted for identification.

Properly trained and equipped gemologists can distinguish between natural diamonds and synthetic diamonds. They can also identify the vast majority of treated natural diamonds, two exceptions being a small minority of HPHT-treated Type II diamonds and some artificially irradiated green diamonds. "Perfect" crystals (at the atomic lattice level) have never been found, so both natural and synthetic diamonds always possess characteristic imperfections, arising from the circumstances of their crystal growth, that allow them to be distinguished from each other.[74]

Laboratories use techniques such as spectroscopy, microscopy and luminescence under shortwave ultraviolet light to determine a diamond's origin. They also use specially made machines to aid them in the identification process. Two screening machines are the DiamondSure and the DiamondView, both produced by the DTC and marketed by the GIA.[75]

Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. CVD diamonds can usually be identified by an orange fluorescence. D-J colored diamonds can be screened through the Swiss Gemmological Institute's[76] Diamond Spotter. Stones in the D-Z color range can be examined through the DiamondSure UV/visible spectrometer, a tool developed by De Beers.[74] Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds.