Why You Should Care About A Diamond's Fluorescence

Author Sue Davidson, G.G.
Date Feb 15, 2021

Buying a diamond isn't an easy task. Diamonds are mined from the ground and each one is completely different and has its own unique characteristics. Because of this, it's important to know some of the technical differences between diamonds so that you can easily differentiate them from one another.

The best way to ensure that you get an amazing diamond is to read up and get educated as much as possible before stepping foot into a store. We always recommend starting with the Four Cs of diamonds, but there are other smaller factors to consider when purchasing diamonds.

A diamond's fluorescence, for instance, is often a detail that is overlooked. Fluorescence can make no difference or can have a big impact on the appearance of a diamond.

Let's take a look at a diamond's fluorescence so that you can see how it will affect the price and look of any diamond you might want to purchase:

What is fluorescence?

Fluorescence is the reaction of trace minerals within the diamond that cause it to glow when exposed to ultraviolet light. A diamond can have fluorescence in a variety of colors depending on the minerals present in the earth during crystalization. The various colors and strengths that a diamond fluorescences can vary from red, orange, blue, and yellow. Blue is the most common fluorescence color in gem quality diamonds,

On a GIA Diamond Grading Report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV, which is an essential component of daylight.

Many diamonds emit a visible light called fluorescence when exposed to ultraviolet radiation. Although invisible to the human eye, UV radiation is everywhere. Sunlight contains it. Fluorescent lights emit it, too. Under the right conditions, you can see some fluorescence in about 35% of gem diamonds.

Why should you care about this when buying diamonds?

A diamond's color refers to how much a shade of color such as yellow is present in the stone. Great diamonds are essentially "colorless" or void of any yellow or other color. Diamonds that are more yellow (and not the good kind of yellow like fancy diamonds) will be cheaper but they aren't as desirable. But, strong blue fluorescence can make a light yellow diamond look closer to colorless in sunlight. Blue and yellow are color opposites and tend to cancel each other out, so blue fluorescence masks the yellow color. However, the fluorescence can in some cases affect the diamond’s transparency making the stone look cloudy or “oily,” which can lower its value.


So, is fluorescence in diamonds actually a good or bad thing?

Well, it can be either good or bad depending on what is important to you. Fluorescence in a diamond has been debated for many years amongst jewelers and will continue for years to come. There are jewelers that choose to sell only non or minimally fluorescent diamonds. This belief is based partly on allowing only the true color of the diamond to be offered and sold with consistency. The preference to buy or sell a diamond that exhibits fluorescence is a personal one, as a diamond’s appearance must be taken as a whole.

As a wise consumer, here is some interesting information that may help you discern what is best for you.

Fluorescence can be negative if it is so strong that it alters the appearance of the diamond to a milky or oily look. Not in all diamonds, but in about 10% of diamonds in the market place, fluorescence is so strong that the stone doesn't look as transparent and “crisp” as it should.

If a diamond is tinted in color (like K, L or lower on the color scale) fluorescence in a diamond can sometimes make the color appear better than what it actually is graded as. Ask to see a diamond of equal color without the fluorescence side by side in the same lighting to visually compare for yourself.

Avoid getting scammed

A generation or two ago, diamonds were referred to as “Blue White” if they were colorless. Some unethical jewelers abused the terminology and were taking diamonds with a strong blue fluorescence (with color grades lower than an “F”) and selling them as “Blue Whites”. This is an old term that is now carefully controlled by the FTC because of misuse and scams in the past.

It isn’t ethical and upstanding when jewelers misrepresent the true color of the diamond and try to sell it as something it isn't. If you are told, “fluorescence, it is definitely a good thing. It makes the diamond look whiter.” Beware! Be sure to ask to see the diamond in different lighting.

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