Fluorescence

Fluorescence is the visible light emitted by a diamond when exposed to ultraviolet radiation (black light). Ultraviolet radiation is invisible to the human eye, but is contained in sunlight and florescent lights. The most common color emitted by a diamond with fluorescence is blue, but white, yellow, and orange are also seen. Thirty five percent of gem diamonds emit fluorescence. This characteristic is included on a diamond certificate as an identifying characteristic, but is not a factor in determining color or clarity.