What is Florescence and How Does it Affect the Value of a Diamond?

What is Florescence and How Does it Affect a Diamonds Value?

 Florescence is the affect caused by ultra violet light on a diamond.   Diamonds with florescence may glow blue (or rarely other colors) when an ultra violet light is shone on them. This “glow” disappears when the light is removed.  It has been documented that of all the stones submitted to a lab for grading, 25% – 35% have exhibited some sort of florescence.

florescence tester
Diamonds Being Tested for Florescence

Why is this important?  

This is just one identifying characteristic that most labs check and make note of. They will note the color of florescence and the intensity. Most florescent diamonds will emit a blue color, but yellow and other colors have been identified.  Intensity ranges from very slight to very strong.  Keep in mind florescence can only been seen under ultra 

Ranging from None to Very Strong

It is important to note the color and intensity of the florescence because it may affect the appearance and the value of the diamond.  It is believed that of all florescent diamonds, only 10% of those show colors and strengths that affect it’s appearance.

One big caveat before I proceed on this topic… Nothing is diamonds is absolute. Two diamonds with the same color and intensity of florescence may appear totally different. So, use this guide with a grain of salt because in reality, you would need to see the diamond and how, or even if, it is affected to determine how florescence affects the price.

The bottom line is in some instances the characteristic of having florescence in a diamond may cause it to be milky or cloudy. The more milky or cloudy, the more it will affect the value.  

Diamonds Shown Under Strong Sunlight
slight cloudiness on florescent diamond
Notice a Slight Cloudiness on the Diamond on Right Under Showroom Lights








On the other hand, on stones with a slightly yellow appearance, say J color or lower, having some florescence may actually make the stone appear whiter, and most dealers will pay MORE for those.

How Do I Know and What Do I Look For?

The rule of thumb in the industry is three things: 

1.higher the color

2. the stronger the florescence

3.the higher quality of the stone 

will have more affect on the price.

  1. The Higher the Color, Why does it matter what color?

Florescence tends to be more obvious in higher colors.  And because the more it affects the stone, the more deduction in price.  In colorless stones you will have more of a cloudy affect than those that may be nearly colorless.

As previously mentioned, diamonds that have a little color, such as J or lower, florescence may actually make them appear more white, hence they command a higher price.

2.  The Stronger the Florescence

Obviously the more intense the florescence the more it will affect the diamond. For example if I have two colorless diamonds one with slight florescence and one with strong, you would expect the strong to be more cloudy than the slight.  However, see caveat above, nothing in diamonds is absolute.

3. The Higher the Quality of the Diamond

The higher the quality of the diamond, generally speaking, means a higher price per carat.  Having said that, it makes sense that a more expensive diamond will have more a discount than a less expensive diamond.

How Much Discount Does Florescence Add?

In most cases, in the  medium to low qualities you will see almost no deduction in price. In high quality diamonds Like D-F VVS-IF, you may see 10%-15% deductions in price. It all depends on how it affects the appearance of the diamond and the perception of value in the mind of the buyer.

The Bottom Line

If you cannot see it, don’t buy it. You must go to a diamond dealer that can show you diamonds side by side for you to compare. Images online, and even movies in some cases, do not show the true brilliance of a diamond. Those images and movies are taken under perfect lighting conditions and do not replicate every day appearance.

Don’t get turned off because you see your diamond, or a diamond you are considering has some florescence. By far most have no or little affect on it’s brilliance.  Look at the diamond not only under the lights on the showcase in the store, but in the center of the room, away from the bright lights. But make sure you look at more than one diamond, because without something else to compare it to, you will not be able to see the difference.  Make sure you visit a dealer that can explain and show you the differences in what you are seeing. In taking these simple steps you can look, compare and choose the diamond that is best for you.

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