What is Diamond Fluorescence and How Does it Affect Value?

Some diamonds experience the presence of a natural phenomenon called fluorescence. But what is diamond fluorescence, how does it affect your diamond, and is it good or bad in relation to its value? Let’s explore the answer to all these questions and more below.

Fluorescence may not be one of the 4Cs, but it is still one of the more important characteristics to be considered in a diamond. The presence of fluorescence, or the lack of it, can impact the overall beauty, and therefore the value, of a diamond. While there are many different qualities a diamond can possess, even an ideal diamond - vibrant, bright, and full of life - with excellent clarity, color, and cut can be less valuable because of the presence of fluorescence. So, what exactly is diamond fluorescence, and why does it have such impact on a diamond’s value?

What is Diamond Fluorescence, and is it Good or Bad?

Fluorescence is the impact that UV light has on a diamond, caused by the incorporation of natural elements such as boron, nitrogen, or aluminum, during the formation of the diamond billions of years ago. The electrons from these elements absorb energy from UV lights, which causes them to release the energy in the form of photons in order to return to their natural, stable state. When we see the glow of a diamond under these conditions, we are witnessing its fluorescence.

Diamonds with Faint or Medium fluorescence can have the appearance of a slight haziness. Usually fluorescence is blue in color. Less often, a diamond can have yellow or even white fluorescence (other colors too). Diamonds with Strong - or Very Strong - fluorescence can appear quite cloudy, milky or hazy to the naked eye, and emit a prominent and saturated glow in the presence of UV light. Only about ten percent of all diamonds have some level of fluorescence.

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Recently, the presence of fluorescence in any amount has been greatly scrutinized by the trade and the public alike. It was not always this way. In fact, only twenty years ago, unless a diamond’s appearance was significantly affected by the presence of fluorescence, most buyers didn’t mind the rather inert visual impact. Only recently has this quality pushed the value of diamonds that exhibit it downward. Many would say that it’s overkill that these diamonds are devalued at all.

So, is diamond fluorescence good or bad? Well, that depends. The more expensive diamonds (large and high color, think D-E-F) are far more valuable when they exhibit no fluorescence. But for most other diamonds, especially diamonds with Faint fluorescence, this phenomenon rarely impacts the diamond’s visual nature. So, the presence of fluorescence, while never considered positive by itself, sometimes has little or no negative impact, depending on the other characteristics of the diamond and the appeal of the overall beauty.

How is a Diamond’s Fluorescence Grade Determined?

The Gemological Institute of America (GIA) will grade a diamond’s fluorescence based on its intensity. The grades on the diamond fluorescence scale from best to worst are:

  • None: Diamonds with no fluorescence present will receive a grade of None.
  • Faint: Diamonds with Faint fluorescence exhibit a very slight amount of fluorescence. It is usually not detectable to the unaided eye, and can emit a very subtle blue hue under UV light.
  • Medium: Diamonds with Medium fluorescence will have a stronger blue glow under UV light. It is usually not detectable to the unaided eye, but can cause a diamond to appear slightly, cloudy, milky, or hazy to the naked eye.
  • Strong: Diamonds with Strong fluorescence emit a substantial and intense blue hue under UV light, and can cause a diamond to appear very cloudy, milky, or hazy to the naked eye.
  • Very Strong: Diamonds with Very Strong fluorescence exhibit a prominent and saturated blue hue under UV light and can cause a diamond to appear substantially very cloudy, milky, or hazy, to the naked eye.

“So, is diamond fluorescence good or bad? Well, that depends. The more expensive diamonds (large and high color, think D-E-F), are far more valuable when they exhibit no fluorescence. But for most other diamonds, especially diamonds with Faint fluorescence, this phenomenon rarely impacts the diamond’s visual nature.”

How Does A Diamond’s Fluorescence Affect its Value?

The short answer is that any presence of fluorescence in a diamond will negatively impact its value to some degree. The greater the fluorescence, the more it adversely affects the monetary value of the diamond. Diamond sellers routinely discount high color diamonds with strong fluorescence by anywhere from 5% to 40%, for example, as compared to similar diamonds with no fluorescence. So, the prices of two very white diamonds, with otherwise similar characteristics, can vary greatly depending on the amount of fluorescence present. This is in part because fluorescence, like inclusions or blemishes, can be essentially be thought of as a flaw, especially in more expensive diamonds, and a milky appearance will impact the brilliance, and even the color, of a diamond.

Lower color ranges aren’t impacted in quite the same way as their higher color counterparts. While fluorescence never adds value, the appearance of some fluorescence in diamonds lower in color (say J-K-L and down) can actually fool the eye into seeing a better color than its GIA color grade shows.

It’s important to note that the presence of diamond fluorescence is not always discounted in the same way by every diamond dealer. Even though the GIA quantifies the amount of fluorescence a diamond has by various degrees, diamonds with the same grade in this regard will be more greatly appreciated, and therefore more highly valued, by trained buyers who recognize whether the visual impact is substantial. That is why CIRCA must physically inspect the diamond you wish to sell before offering a final price. CIRCA’s diamond buyers are uniquely qualified to evaluate your diamond for all its characteristics - including the 4Cs, fluorescence, and more. We buy diamonds every day, and we buy a lot of them. Our experience allows us to look for the nuances in your diamond which can help maximize its value. Our expertise, coupled with our unique global sales distribution, allows us to pay the very best price when you want to sell your diamond.

For the best value and immediate payment, sell your diamond to CIRCA by scheduling a visit at one of our 12 locations worldwide.