The term ‘fluorescence’ describes the visible light that emits from a diamond under long-wave ultraviolet (UV) or ‘blue’ light. In the same way that your white t-shirt would glow under a UV light, diamonds can show varying reactions as well – from no effect at all to a strong glow (see image above).
Fluorescence is a common natural characteristic of many diamonds and does not affect the structural integrity of the diamond in any way. According to the Gemological Institute of America (GIA), approximately 25% to 35% of diamonds exhibit fluorescence to some degree and 10% exhibit medium, strong or very strong fluorescence.
Keep in mind this will only be seen under very strong UV light conditions.
In the vast majority of diamonds, the colour reaction to UV light is blue, because blue is the complementary colour to yellow.
In rare cases, the reaction can be yellow or another colour.
In diamond grading reports, there are five categories of fluorescence:
None, Faint, Medium, Strong and Very Strong
Diamonds that exhibit extremely strong fluorescence that can display an oily or hazy appearance. At Labrowndiamonds.nz we will only show diamonds with NIL or FAINT fluorescence grades.
Image Courtesy: GIA