Most diamonds found in nature do not fluoresce. It has been established over the years, through extensive testing that approximately 30% to 35% of all natural diamonds exhibit some degree of fluorescence when exposed to UV light.
A diamond might fluoresce under a bright sun, at the dance floor or in other places where strong fluorescent or black light is present. Fluorescence is a temporary phenomenon and once the UV light source is turned off, the diamond stops fluorescing.
Diamond grading reports in general describe the intensity in 5 grades of fluorescence as: None, Faint, Medium, Strong and Very Strong. If the fluorescence level is Medium, Strong or Very Strong, the 'colour type' of the fluorescence is also stated on these reports
If you’re still wondering what diamond fluorescence is, think about how ultra-violet light makes your whites look whiter and some of your teeth glow at the discotheque. In the same context, you are reading this because you want to know when a diamond fluoresces or radiates a glow, is that good or bad or neutral for your diamond.
Here is an attempt to demystify some of the misinformation and conjecture surrounding fluorescent diamonds, so read on . . .
Causes & Effects of Fluorescence
Fluorescence in diamonds remains a widely misunderstood concept, both at the trade and consumer level. It’s been a frequently debated topic within the diamond industry and the opinion of experienced jewellers on this subject tend to differ.
When it takes over a billion years to form in the earth’s mantle, you will likely absorb atomic quantities of your neighbouring minerals and gases. Trace elements absorbed in these minuscule quantities during the growth phase, such as aluminium, boron or nitrogen can cause diamonds to fluoresce. The variations caused in the atomic structure of the diamond crystal then act as a trigger.
Ultraviolet light, which consists of high-energy waves, then does the trick, causing the electrons of these trace elements to pop into higher energy states. Electrons in these excited states continue to release that stored energy as light so long as the UV light is present. Remove the UV light, and the excited electrons gradually return to their original state.