The Fluorescence is a characteristic that makes some diamonds appear to change color when they are exposed to the ultraviolet light that surrounds us every day in sunlight and in the light produced by fluorescent light bulbs. The Diamond Fluorescence refers to how a diamond responds when subjected to ultra-violet light. Some diamonds, when they are exposed to UV light, glow different colors. 

 

CGL grades Fluorescence with 5 different ratings:

None

Faint

Medium

Strong

Very Strong