Diamond color is all about what you can’t see.
Diamonds are valued by how closely they approach colorlessness; the less color, the higher their value.
The GIA Color Scale extends from D (colorless) to Z (light yellow, brown or grey). Although many people think of gem quality diamonds as colorless, truly colorless diamonds are actually very rare. Most diamonds used in jewelry are nearly colorless with tints of yellow or brown.
What is fluorescence? It is the visible light some diamonds emit when they are exposed to invisible ultraviolet (UV) rays. On a GIA diamond grading report, fluorescence refers to the strength or intensity of the diamond’s reaction to long-wave UV, which is an essential component of daylight. The light emitted lasts as long as the diamond is exposed to the ultraviolet source.