All About Diamond Fluorescence

Fluorescence in a diamond will make the diamond “glow” or emit a low level of light. Most light is usually blue, but it may also appear green, yellow, or even red occasionally, but only when that diamond is exposed to ultraviolet (UV) light. UV light is invisible to the human eye and is a natural part of both everyday sunlight and the “black light” sometimes used in discos or clubs. The emitted light or “glow” will last only so long as the diamond continues to be exposed to the UV light.

How does it impact the look of the diamond?

Most fluorescence does not impact the look of the diamond at all unless it is particularly strong. Gem labs rate fluorescence as none, faint, medium, and strong or extremely strong. Strong or extremely strong fluorescence in a diamond may make it appear somewhat “hazy” or “oily”. This is rare and affects only about 0.2% or fewer diamonds submitted for grading. It is even rarer for lab-grown diamonds. For the most part, fluorescence has no impact on the appearance or value of a diamond unless it is very strong.

What causes fluorescence in diamonds?

Diamond fluorescence is caused by submicroscopic shifts/substitutions in the diamond’s structure. These do NOT compromise the structural integrity of the diamond. Diamond experts and graders will mention fluorescence as a feature of a stone that has it but unless unusually strong, it is neither a positive nor a negative aspect of the stone.


“Should I buy a diamond that contains Fluorescence?”
Since fluorescence has neither a negative nor positive impact on the diamond’s price or appearance, especially in better color grades, the choice is yours. There are those in the mined diamond community who have recently tried very hard to sell fluorescence as a positive characteristic. That may be because they have many fluorescent diamonds to sell. Many people believe that slight fluorescence in a lower color grade (J or lower) may help the stone to appear lighter. While you are free to decide for yourself, color, clarity, cut, and carat weight are all universally considered to be more important factors in the diamond’s appearance and value than fluorescence. Gem grading labs consider fluorescence a feature that has little or no effect on the price range or appearance of the diamond.

“Is diamond fluorescence good or bad?”
Diamond fluorescence is neither “good” nor “bad”. In fact, we should avoid using terms like “good” or “bad” in relation to any diamond. No diamond is good or bad. They are more or less expensive or more or less attractive but never “good” or “bad”. Fluorescence in a diamond is a feature of the stone and depending on the degree, it may make the diamond more or less attractive based almost entirely on personal taste. Unless the fluorescence is strong or very strong, it will have no effect on either the value or the desirability of the diamond.

“Can diamond fluorescence improve the color of my diamond?”
If your diamond is a high color grade such as G or better, then the answer is that it will not. If it is a lower grade such as J or lower, the answer is “perhaps”. We say perhaps because depending on how much strong fluorescence is present, it may make a darker diamond appear a bit whiter in sunlight. However, strongly fluorescent diamonds may also appear hazy or oily in indoor lighting. Mild fluorescence will have no impact on appearance.

“How can I know the level of fluorescence in my Clean Origin diamond?”
If a diamond sold by Clean Origin is fluorescent, it will be shown both in the item description and on the diamond certificate. However, most diamonds sold by Clean Origin are not fluorescent.

“How is diamond fluorescence measured?/ Can diamond fluorescence be measured?”
Gem labs routinely rate fluorescence as none, faint, medium, and strong or extremely strong. That is the only real measure of fluorescence.

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