None | Faint | Medium | Strong | Very Strong
The fluorescence of a diamond refers to a soft, glowing, light-blue emission that is visible under ultraviolet light. The simplest analogy to describe the effect of fluorescence on a diamond would be the colour of a white shirt under UV light at a nightclub. The Gemological Institute of America (GIA) reports diamond fluorescence with five grades: None, Faint, Medium, Strong, and Very Strong.
The degree of fluorescence can be observed under any standard ultra-violet light – but only in a dark room. Hence, in the majority of cases, fluorescence has no effect on the stone in normal daylight. The minor percentage of diamonds that are affected tend to be in Strong or Very Strong Fluorescence category. It’s in these diamonds, a very light haziness is sometimes observed – affecting the lustre of the diamond.
While we know that the price of a diamond is normally based on the 4 C’s – cut, colour, clarity, and carat weight – manufacturers consider fluorescence a ‘defect,’ and price it lower than their non-fluorescence counterparts. Fluorescent diamonds with a high colour and clarity grade have a larger degree of discounts. Consumers focussed on gaining the most value for their money should consider diamond options with fluorescence. Should there be any doubt, your gemologist will be able to clarify whether the fluorescence has any effect on the selected diamond.
Colour & Fluorescence | Money-Saving Tip!
If you are opting for a lower colour grade - I, J, and/or K as certified by the GIA, selecting a diamond with fluorescence could be advantageous. Theoretically, the 'blue' fluorescence reacts against the 'yellowish' colour of the diamond. Hence, when viewed face-up, the colour of the diamond is perceived to of a higher colour grade than it is. Simply put, the diamond appears more transparent, therefore giving it a better overall lustre.