Does the ultraviolet component of the light used for grading affect the color grade of the diamond?

GIA uses a standard set of lighting conditions for the color grading of all diamonds. The light source used is designed to simulate natural sunlight, which contains a component of ultraviolet radiation. In rare cases, a diamond can emit strong or very strong blue fluorescence when exposed to ultraviolet radiation—in such instances that fluorescence may temporarily and slightly affect its color appearance.