When it comes to selecting the quality of your diamond, the Four C’s are usually all the discussion.
I suggest paying attention to all of these factors (most importantly Cut), but there is another one worth noting: Fluorescence.
While not usually a big issue, it can affect the price of the diamond up to 20%!
What is Fluorescence?
About 1/3 of all diamonds fluoresce, meaning they emit light when exposed to UV light. You can easily find out if your diamond is fluorescent by holding it under a black light (it will give off a glowing blue color). Almost all fluorescent diamonds exhibit a blue color, though it’s possible to see green, yellow, orange or red.
In GIA terms, the fluorescence of a diamond is graded anywhere between None, Faint, Medium Blue, Strong Blue, Very Strong Blue. Fluorescence does not affect the integrity of your diamond but it can affect the color and sometimes the brilliance if it is too strong.
So…is Fluorescence good or bad?
It really can be both, or neither. Confused yet? Hang in there!
If a diamond has None or Faint fluorescence, you shouldn’t be able to tell any difference in the appearance. This is good if the diamond already has G-H color or better.
If your diamond is below H color, a medium blue fluorescence can actually make it look whiter than it is. For example, a J color stone that is really well cut with medium blue fluorescence could pull off a really nice look in a white gold ring and save a little money.
I would not recommend buying a diamond with strong or very strong fluorescence because it can give the diamond a milky/hazy look. The diamond will look white, but for some reason it doesn’t look quite as sparkly or clear as it should.
In the end, you’re best bet is to get a diamond with a decent color and keep the fluorescence to a minimum.