Diamond fluorescence refers to the diamond tendency to disperse a soft bluish glow when exposed to ultraviolet light. “A diamond should not have strong fluorescence.”That’s what is often claimed by many diamond experts. However, we have got to be careful with this statement : faint or moderate fluorescence does not affect the diamond’s look, which is proved by a GIA study. Moreover, some customers even prefer a faint fluorescence, because it balances the yellow colour of some of the less expensive stones.
What is diamond fluorescence?
Diamonds have many properties and characteristics. The natural blue fluorescence is one of them. When gem grade diamonds are exposed to ultraviolet light, electrons in the diamond crystal excite and a bluish glow can be visible. This phenomenon occurs in a third of all gem grade diamonds.
The fluorescence is only visible under the black light while recent (GIA) studies have proved that it doesn’t influence the appearance of the diamond. In earlier times people didn’t even didn’t want to buy diamonds with a fluorescence. While they were a trend in the fifties under the name ‘blue white diamonds’, demand dropped in the seventies.
Diamond with fluorescence can change the diamond colour sometimes, because the UV radiation is also a component of daylight and is present in fluorescent place. Note that the blue shine is often desirable (it makes yellow diamonds whiter).
The effect on the diamond value
You can find the ‘fluorescence indication’ (inert, faint, negligible, medium) on different diamond reports such as the GIA diamond reports. Diamonds with a strong fluorescence are priced lower than diamonds without fluorescence.
In general, diamonds with colorless grades (D-E-F) or near colorless grades (G-H-I-J) are cheaper when they disperse fluorescence. Faint yellow grades (K-L-M) are higher in price when exhibiting fluorescence.
However it is often said that fluorescence has a negative impact on colourless diamonds and a positive impact on faint yellow diamonds, you don’t have to influence your choice to much based on this information.