Fluorescence
fluo·res·cence | flu̇-ˈre-sᵊn(t)s
noun
A luminescence that appears when certain diamonds are exposed to ultraviolet light
A common phrase applied to diamonds is fluorescence. This phrase generally refers to the visible glow emitted by an object. Diamonds can fluoresce when a UV light source is applied to them. This can be something as simple as the sun or a fluorescent lamp. The resulting glow is most often blue, but can also be yellow or orange in certain lights and for certain diamonds. Only about 25-35% of all diamonds show any degree of fluorescence, and while it is not considered one of the primary grading factors like the 4Cs, it is an identifying characteristic. Fluorescence is defined by the intensity of the glow, ranging from none to very strong. It is noted in a diamond’s grading report if it is medium or higher on the scale.