Fluorescence is a form of luminescence. This is a term describing any emission of light by a substance that is not the direct result of incandescence. Diamonds that are exposed to ultra-violet light (long wave or short wave) may glow, showing a certain degree of fluorescence. Fluorescence is caused by electron activity inside a gemstone, which results in the emission of energy. Should this energy have a wavelength in the visible portion of the electromagnetic spectrum, fluorescence results. Impurities in a diamond could create structural irregularities that could cause fluorescence. Blue fluorescence is the most common type of fluorescence in diamonds. In the trade, some stones are known as Premier diamonds. Click here to read the full article. Fluorescence