What is diamond fluorescence? Is it good or bad? Does it influence diamond quality? These are questions often raised when shopping for diamonds. Let’s go into details and make an informed decision.
What is Diamond Fluorescence?
Diamond fluorescence is the ability of the stone to emit light and change its colour when subjected to ultraviolet (UV) rays.
It’s worth mentioning that not all diamonds fluoresce. Only around one-third of all diamonds exhibit some kind of fluorescence.
The cause of fluorescence is hidden within the stones. Diamonds contain different chemical elements, which can glow in the dark depending on their concentration.
Diamonds can fluoresce in different colours such as blue, yellow and orange, though the first one is the most widespread colour and non-blue fluorescence is extremely rare.
Gemological Institute of America (GIA) describes a diamond’s fluorescence by its intensity:
- None
- Faint
- Medium
- Strong
- Very Strong
Whether the diamond is fluorescent and what colour it glows should be listed on the stone’s grading report.
Does Fluorescence Affect Diamond Quality?
The effect of fluorescence on the quality of a diamond is a controversial topic.
GIA has conducted a study on fluorescence and concluded that it does not affect the quality of the stone for an average observer.
However, some jewellers claim that in their experience, diamonds that exhibit strong fluorescence tend to appear foggier. Others say that it doesn’t have a significant effect on the appearance of diamonds.
That’s why you need to decide for yourself if a particular diamond looks good to you. If you think that the stone looks a bit foggy just go with another one, but don’t let fluorescence alone influence your decision.
Fluorescence and Diamond Prices
Since strongly fluorescent diamonds are considered by some people to be negatively affected, these stones usually have lower prices compared to similar non-fluorescent diamonds.
If you see a blue fluorescent diamond, check if you like its colour, clarity and cut. This may be a bargain and you may save some money.
In some cases, blue fluorescence can mask and improve yellow tint of lower colour grade stones (especially I to M). As a result, near colourless to faint yellow diamonds with Medium to Very Strong fluorescence may have a slightly higher price per carat than similar diamonds with no fluorescence.
Diamonds with higher colour grades (D to H) with blue fluorescence are considered less desirable. Some believe that blue may cause oily appearance in the diamonds if fluorescence intensity is Very Strong. In fact, not all diamonds look oily with Very Strong blue fluorescence, but they all cost less than diamonds that do not have fluorescence.
Considering Fluorescence When Buying Diamonds
When shopping for diamonds, ask the jeweller to show the stone under both UV and normal lighting. Don’t forget to look at the stone when it is exposed to daylight as well. Sunlight contains UV rays, which will bring out your stone’s fluorescent colour.
If a stone is fluorescent, compare it with a non-fluorescent diamond of similar quality and check if you can see any difference in colour and clarity.
In general, fluorescence is neither good nor bad. You may like it, or you may not. The most important is to love what you end up with.
Cover image credit: Koichi Yajima / EyeEm / Getty Images
