The beauty of a natural diamond is best captured when light shines through the stone. How the diamond behaves in this light is important to its appearance and truly its value. Fluorescence is something that is often evaluated in a diamond and refers to the way a diamond responds when subjected to ultra-violet (or black) light.
Fluorescence is truly an amazing phenomenon as it can cause a diamond to glow different colors. The most common color in Fluorescence is blue, although in very rare occasions, a diamond has been known to glow white, yellow, green or even red in color. It is strongly advised that the latter be avoided unless the diamond color matches the hue of the Fluorescence.
Roughly one third of diamonds have Fluorescence, an effect very much akin to what your white shirt will do under a black light. In a diamond, this Fluorescence can be faint or very strong. According to one GIA survey, fluorescent diamonds are favored over non-fluorescent stones, especially in lower colors H-Z due to the fact that fluorescence can sometimes make the diamond appear to have a better colour than it really does, but this can even occur in higher diamond colors, such as D, E, F or G graded diamonds.
Interestingly, Fluorescence has a somewhat tainted past in the diamond industry. A number of years ago, D-F colorless fluorescent diamonds were highly prized and referred to as “blue-white”. Unfortunately, sales professionals abused the term by using it to refer to any diamond with Fluorescence and trade practice laws in the United States outlawed the use of the term, then other countries followed suit.
The element of Fluorescence in diamond grading is interesting as the GIA light used in testing emits a small amount of ultra violet light, which can cause the diamond Fluorescence to be assigned a better color grade. At the same time, and unfortunately, a number of less experienced diamond sales professionals are not skilled in explaining the phenomenon of Fluorescence and therefore a Fluoro comment on a diamond grading card can make the diamond worth less, even if its quality can withstand such a grading.
Why?
Fluorescence is visible light emitted by elements within the stone when a diamond is under the higher energy source provided by the UV light. This distorts the diamond effect. In some cases, it makes the diamond appear to be oily or cloudy, which is considered to be very bad by both the GIA and the average consumer.
By contrast, one GIA study found that such diamonds are extremely rare and this could play into value. In this same study, unfortunately, there was not enough of the same type of diamond to examine for further investigation. As a result, this concept is still up for debate and has caused considerable controversy in the industry.
While the information regarding Fluorescence can be confusing, there are three elements to consider that are always consistent:
1) Strong blue Fluorescent diamonds generally appear hazy
2) Medium blue Fluorescent diamonds rarely appear hazy
3) Slight blue Fluorescent diamonds never appear hazy
When selecting a diamond with Fluorescence, seek a diamond with a Fluorescence grading of FAINT or up to SLIGHT to gain the best and most brilliant diamond appearance in natural light.
There are generally two schools of thought in the industry when it comes to Fluorescence:
- Avoid it at all costs
- Up to and including a SLIGHT grading is acceptable as this is barely visible to the naked eye in normal lighting conditions – or normal everyday wear.
Personally I prefer to source diamonds without Fluorescence as I have found that it will give you greater peace of mind in the long term. In the off chance your diamond ring or jewellery has to go through a UV light, no Fluorescence means there is no chance of the diamonds starting to glow all sorts of funny colours. You won’t have to worry about this phenomenon, or worry that your diamond will appear oily or hazy when viewed in natural sunlight.
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