Of all the quality gradings that diamonds have fluorescence is probably the most argued about and most misunderstood.
In our opinion fluorescence is a very minor concern when choosing a diamond but still needs to be considered in your purchase. Fluorescence will only impact the appearance of a diamond negatively in a very minimal number of circumstances and in some cases can actually improve the appearance of a diamond. This does have an effect on the price and there are a few general rules to follow when selecting a diamond.
What is fluorescence?
Fluorescence is a visible light that is emitted from all diamonds in different intensities when exposed to ultraviolet (UV) light which is in natural sunlight. To actually see the impact of this in a diamond you need a dark room and a significantly strong UV light source, so next time you go into a nightclub you may want to check your diamonds. Fluorescence occurs due to the vibration of free bonding electrons within the carbon atomic structure of the diamond when exposed to UV light, the more free electrons available the stronger the fluorescence. Even though these electrons are unbonded it in no way has an impact on the structural strength of the diamond. Of all diamond about 65-75% have very faint to almost nil fluorescence which do not produce enough light to create an effect. Of the diamonds that do have a significant fluorescence only some will actually be visibly noticeable.
How common is fluorescence?
Only about 10% of all Medium to Very Strong fluorescing stones will actually have a visible impact. Fluorescence is generally a pale blue colour but in some diamonds can actually be green, yellow or white. Because fluorescence is blue in lower grade diamonds coloured I and below fluorescence can actually help make the diamond look better as the blue light will counteract the tinted yellow colour of the diamond. Diamonds coloured G and H are quite fine to have a medium or strong fluorescence as it still help make the diamond appear whiter and there is very little negative impact on the diamond.
What impact does fluorescence have?
The only time that we find where fluorescence will become a problem and it is still only very minor is in diamonds with a strong or very strong fluorescence and coloured D – F. These diamonds are already very white and quite transparent, in full sunlight a discerning eye can sometimes pick up that the diamond will exhibit a slight milky or hazy appearance because of the fluorescence.
So what does fluorescence mean to my purchase?
In very large and very difficult to find diamonds there may not be any option with the fluorescence grade that we can choose to get everything else that we would like which is still fine as fluorescence really is the least impact of all the diamond qualities. A diamond with a Nil fluorescence is considered to be the most ideal so having a bit of fluorescence in a diamond can help reduce the price of the diamond without affecting the appearance. To be in the safe zone we recommend that for any colour grade a Medium or lower is preferable and up to strong for colours below a G and to avoid a Strong or Very Strong in D- F coloured diamonds if possible.