Labs Refute Claims HPHT Escaping Detection

RAPAPORT... Major gemological laboratories have rebuffed claims that detection machines are failing to spot synthetic diamonds that have undergone irradiation.In a trade alert last week, Diamond Services argued that the treatment, generally used to alter the color of a stone,can mask the phosphorescence effect when diamonds created using High Pressure-HighTemperature (HPHT) undergo scanningat room temperature.While detection machines can often identify HPHT diamondsbecause they phosphoresce - or glow - under ultra-violet light, certain devicesfail to spot some of those stones that have been subject to irradiation, the Hong Kong-based diamond-technology company argued. However, De Beers and the Gemological Institute ofAmerica (GIA) have denied the impact of such a phenomenon on their machines'ability to sift out HPHT synthetics."The International Institute of Diamond Grading and Research (IIDGR) confirms that its instruments AMS2, SYNTHdetect,DiamondView and DiamondSure are all effective at screening HPHT synthetic materialwhich has been irradiated and is tested at room temperature," the De Beers-owned grading unit said in astatement last week."Any business using these devices can have full confidencethat any such material will be detected without the need to undertake tests atdifferent temperatures," it added.Meanwhile, although detection devices based onphosphorescence may not be able to detect some HPHT-grown irradiatedsynthetics, the GIA's machines can spot them, the Carlsbad, California-headquarteredlaboratory stressed."The ability of the instruments that GIA uses todifferentiate natural diamonds from HPHT and CVD [chemical vapor deposition]-grownsynthetic diamonds, including the GIA iD100 gem-testing device and the GIAMelee Analysis Service, is not affected by irradiation treatment," the GIA toldRapaport News.Examiningdiamonds at the temperature of liquid nitrogen can be an extremely accurate method of detecting synthetics, while a technique called Raman spectroscopy is asimple way of spotting irradiated diamonds, according to Joseph Kuzi, founderand president of Diamond Services."Our latest findings indicatethat the diamond and jewelry trades should show extra caution, but we do notclaim that irradiated HPHT-grown synthetic diamonds are undetectable," Kuzisaid.Image: IIDGR