Knowledge base

Fluorescence is the visible light that some diamonds emit when exposed to invisible ultraviolet (UV) rays. It refers to the strength or intensity of the diamond's response to long-wave UV light, which is an essential component of daylight. The emitted light persists as long as the diamond is exposed to the UV source.

Approximately 25% to 35% of diamonds in circulation exhibit some degree of fluorescence. However, only 10% of these diamonds exhibit fluorescence intensity that can affect appearance (i.e., intensity reported in laboratory reports as medium, strong, or very strong). In more than 95% of fluorescent diamonds, the color is blue. In rare cases, the reaction is yellow, white, or some other color.

In the vast majority of diamonds, fluorescence strength has no generally discernible effect on appearance. In many cases, viewers prefer the appearance of diamonds with moderate to strong fluorescence. In rare cases, some diamonds with extremely strong fluorescence may appear cloudy or oily.