The fluorescence of the diamond is the visible light produced by the diamond when it is exposed to ultraviolet (UV) / black light. This is produced by the reaction between light’s energy and diamond’s atoms. In the majority of cases, this fluorescence is BLUE.

There are different degrees of fluorescence.  It’s determined by comparing a diamond to exposure and ultraviolet radiation. If the diamond appears dark or opaque to this exposure, it means that it’s not fluorescent. Diamonds with "strong" or "very strong" fluorescence offer a good value (price),  because the price is placed slightly lower in the market. Rarely, fluorescence affect any kind of visual impact on the appearance of the diamond.

The scale used to define the fluorescence of the diamond is as follows:

• None
• Faint
• Medium
• Strong
• Very Strong

In many cases the buyer chooses a diamond that is at a very good price and the reason is that it has fluorescence. In certain cases it may affect the diamond in a negative way. The effects that can occur in a diamond with Fluorescence is that the diamond has a milky or hazy effect. The probability that it affects a diamond increases in diamonds with "Strong" or "Very Strong" fluorescence.

Tip "fluorescence":

When a diamond has K or higher color the blue fluorescence can help the diamond appear colorless.