Diamond Fluorescence

Diamond Fluorescence title

What is Fluorescence

There appear to be a conflicting views regarding diamond fluoresce, some love it, others hate it. But what's the truth? 

Usually, if you're about to purchase a diamond, your jeweller will warn you against buying a diamond with fluorescence. It is a characteristic that can have a significant impact on value and is therefore something that consumers need to carefully consider when shopping for a diamond.

Fluorescence refers to how a diamond responds when subjected to ultra-violet light. Common sources of UV lights are the black light at your favourite nightclub, fluorescent bulbs and the sun. UV light is what makes your teeth whiter, and your black-light posters glow.  It is considered a flaw which reduces the price.


Fluorescence ranges from None to Very Strong. 

Okay, I still didn't get it, What is fluorescence?

Diamonds shine because they reflect light. If their light source is subjected to UV light, the electrons get a crazy high level of energy, which they get rid of in the form of protons... which to us non-physisits just looks like fluorescence. 

Usually the color of fluorescence is blue, but they occur in other colours as well: Pink, (greenish) yellow, green and white. 

Why I should care (Good News)

In 1997 GIA (The gemological Institute of America) published a study where they found that 35% of all gem quality diamonds have some level of fluorescence when exposed to UV lighting conditions. 

Remember how I mentioned that the sun is a source of Ultra Violet lighting? Well, it seems that in day light conditions fluorescence can make a diamond with a lower color (I to M) grade appear "whiter". 

Since fluorescence is considered a flaw, diamonds with fluorescence are usually discounted. 


Why I should care (Not-so-Good News)

According to the same study published by GIA, only 3% of diamonds, with a fluorescence ranging from Medium to Strong Blue appear to be little foggy. The industry would call these diamonds milky or hazy stones.
Now here is where we encourage you, the consumer, to please look at the stone yourself. Beauty is in the eye of the beholder, and if you're not sure about this particular diamond, don't buy it. I've seen quite a few stones where the fluorescence has made a difference in the fire of a stone, but only when the stones are larger than a 0.30 carat. 

Diamonds are still graded by humans, so there is some room for error, especially since these graders use a a special tube light which have a UV component which could stimulate the fluorescence of a stone to make it appear lighter (better) than it is. These findings are confirmed by a second grader, and once that is complete, the diamond receives a certificate (kind of like a report card). 

Diamonds with a higher color grade, D to H, with a bluish fluoresce are often considered less desirable. 

The Fluorescence Spectrum
The fluorescence spectrum

Key takeaway

Don't buy blind. Yes there is a certificate that will let you know what "type" of fluorescence you're looking at, but don't forget to look at the stone yourself. 

Is it bad or not? Neither answer is appropriate. Each diamond is unique, and you really have to see it yourself to make a decision.