Identification Tools Required: Magnification, experience.
How to Identify:
Primary Test: There is no formal test for a grass roots level jeweler or gemologist to positively identify irradiation of a diamond to impart an artificial color. Perhaps the best identification method is to apply experience looking at diamond colors and knowing that natural blue diamonds are extremely rare, as are intense yellow colors among other colors you will find as a result of irradiation treatments. Some of the most often seen colors of irradiated diamonds will be the blue, yellow and green. The intensity of the colors will be one indicator, as will the fact that most treaters use low quality diamonds to irradiate due to the loss of many stones during the volatile radiation process. On rare occasions you can see an intensification of the color at the culet since these diamonds are treated from one direction. Since the radiation source is normally directed at the diamond from the culet, the culet will sometimes show an intensity of color due to the greater exposure to the radiation. Once again, this is an indicator only.
Secondary Tests: Raman spectroscopy is diagnostic for irradiation treated diamonds since the process of the irradiation damaged the crystal lattice of the diamond. This can be an expensive test from the major labs but it is available from the ISG office for a nominal fee.
Repair and Setting: In general can be treated with the same care as any diamond for setting and repairs. Care should be taken with heating as some irradiated diamond colors may change with sufficient heat. Recommend heat sink or removal before direct repairs are attempted to avoid possible color change due to heat.