GIA Report Explains Fluorescence, Why Some Diamonds Glow

In an effort to help educate the public about the little understood phenomenon of ultraviolet fluorescence in diamonds, the Gemological Institute of America (GIA) will include additional information describing fluorescence in every GIA Diamond Grading Report and Diamond Dossier® that carries a diamond fluorescence description of medium or stronger.

The GIA will include an insert that addresses the most frequently asked questions about fluorescence, explains its properties and includes comparison images of diamonds in both natural and UV light to illustrate varying intensities of fluorescence. 

“Fluorescence is the emission of visible light by a diamond when it is stimulated by invisible ultraviolet (UV) rays,” said Thomas M. Moses, GIA’s senior vice president of Laboratory and Research. “It is a common characteristic of diamonds. The diamond simply glows under the UV lights, usually a blue color, which most often stops when the energy source causing it is removed.”

The five terms GIA uses to classify the intensity of the fluorescence are None, Faint, Medium, Strong and Very Strong.

“This insert will help the public better understand diamonds in general, which gives them more confidence and knowledge when making a decision about a diamond,” Moses added.

GIA has additional information on fluorescence on its Web site, including a scientific article, “A Contribution to Understanding Blue Fluorescence on the Appearance of Diamonds,” by Moses, Ilene M. Reinitz, Mary L. Johnson, John M. King and James E. Shigley, which appeared in the Winter 1997 issue of GIA’s Gems & Gemology.