Lecture Demonstrates How to Detect HPHT Treated Diamonds
June 29, 03
At an open lecture about how to identify HPHT treated diamonds, Antoinette Matlins-Bonanno demonstrated a number of simple methods to detect treated diamonds.
With a healthy sense of humor, Matlins-Bonanno guided the crowed who came to hear her at the Harry Oppenheimer Diamond Museum in Ramat Gan last Thursday through a series of demonstrations that give diamantaires easy and cost effective ways to detect heat treated stones. 
Matlins-Bonanno
during a demonstration
One simple example included a small device that detects if white, type 2A, is HPHT treated or not. On top of the device a white diamond is placed, surrounded by silly putty. When turned on, a short-wave light is directed at the diamond.
If the returned light is green, the diamond is treated, if the light is white, the color of the diamond is natural. Other examples checked color stones for their natural color.
What captured peoples attention was the low cost and seeming accuracy of the tests. The small machine that checked white diamonds costs a couple of hundred dollars.
Matlins-Bonanno is the daughter of famed gemologist Antonio Bonanno and a gemologist on her own right who wrote extensively about diamonds and diamond buying.