The American Gem Trade Association’s Gemological Testing Center recently added new options for determining whether diamond coloration is natural or artificial and whether a colorless diamond has been subjected to high-pressure/high temperature (HPHT) treatment.

HPHT treatment (to remove or add color) and color-inducing irradiation are identified through microscopic observation, examination of low temperature UV/visible and Raman spectroscopy, and room temperature infrared spectroscopy. AGTA GTC director Ken Scarratt, who has more than 20 years’experience in colored diamond research, supervised setting up the equipment for these types of testing. AGTA Gemological Testing Center, 18 E. 48th St., Suite 1002, New York, NY 10017; (212) 752-1717, fax (212) 750-0930.