Diamond Fluorescence

Is Diamond Fluorescence Bad?

Some retailers will tell you that fluorescence is bad...is a negative, but many consumers actually prefer diamonds with fluorescence! The truth is that fluorescence rarely affects a diamond's sparkle and brilliance, and in warmer or lower colored diamonds, fluorescence makes them look whiter or more colorless. Diamonds with fluorescence should be graded case by case. You may not even notice fluorescence in your diamonds, unless you are at a nightclub with black lights...Have fun and enjoy the blue glow!

About a third of diamonds exhibit fluorescence, like the fluorescent minerals you have seen in natural history museums or the novelty shop toys under the black (UV) light. The effect is like a white shirt in a discotheque. Fluorescence can be faint to very strong, and the most common fluorescent color is blue. As blue is the complimentary color to yellow, the most common tinted color in diamonds, blue fluorescence can make yellowish diamonds look white or colorless.

See for yourself...

The two photos below show the same 1.34ct diamond with Very Strong Blue Fluorescence. The photo on the left shows what the stone looks like under normal lighting conditions. The photo just to the right shows the same stone mounted in a ring with a UV light pointed at it. The stone faces-up very white in normal lighting conditions, and it appears "whiter" than its I color grade would suggest.

Diamond FluorescenceDiamond Fluorescence
1.34ct I VS1 graded Very Strong Blue Fluorescence by GIA
Photo of loose diamond on left by Whiteflash
Posted by TotalNewbie

Search for diamonds with fluorescence by clicking below and see how many diamonds are fluorescent:

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And now the nitty gritty...

A GIA survey found that fluorescent diamonds were favored over non fluorescent diamonds in both the lower color range AND in the higher colors, (D, E, and F) which are usually discounted by the trade. Many years ago D-F colorless fluorescent diamonds were highly prized and referred to as "blue-white," but sales people abused the term by including any diamond with fluorescence. So, usage of "blue-white" was outlawed by US trade practice laws.

Discounting Fluorescent Diamonds

One may argue for discounting fluorescent diamonds, because the GIA lab grading lights actually emit a small amount of ultra violet light. Thus, fluorescent diamonds might be assigned a better color grade. It is difficult for graders to determine a diamond’s true body color with even a small amount of ultraviolet light in the mix. The counter-argument from the GIA Gem Trade Lab is that UV light is present in many viewing environments, so it follows that color should be graded in realistic lighting.

The most likely reason that fluorescent diamonds are discounted is because many jewelry salespeople are not able to explain the complex phenomenon called fluorescence. When the word “fluorescence” is written on a grading report, the diamond is simply harder to sell. Imagine a salesperson saying: “Fluorescence is visible light emitted by electrons when a diamond is excited by a higher energy source like ultraviolet light or x-rays.” Most shoppers aren’t interested!

Extreme Diamond Fluorescence

Some diamonds have extremely strong fluorescence and appear oily or cloudy like the one in the picture below. This diamond has extremely strong fluorescence in direct (left) and indirect shaded (right) cloudless mid morning sunlight. In direct sunlight it has a strong milky blue cloudiness that makes the stone very dull (photo on left). But on the right side, even in strong lighting, the stone sparkles beautifully.

The fluoro effect in some other lighting can be evident as a bluish tint that does not dull the diamond's brightness or fire. Milkiness is not desirable but the GIA study found them to be very rare. They were unable to find enough cloudy stones to do a study from the 26,010 sample they used.

Diamond Fluorescence
Posted by Garry H (Cut Nut)

When you are considering stones with Very Strong or Extremely Strong Fluorescence, it is wise to compare them side by side with non-fluorescent diamonds in shaded daylight, which has a lot of ultraviolet light. You can also use a UV filter like a small sheet of Lexan.

Faint Diamond Fluorescence

The photo below shows a diamond with negligible fluorescence taken in direct sunlight. Note that diamonds usually appear quite dark when seen in direct sunlight, a fact that alarms many first time diamond buyers. Since diamonds can look dark in direct sunlight, the fact that some fluorescent diamonds get a slight blue tinge should not be a big deal. The diamond below looks very bright and lively with no reduction of brightness or fire.

Diamond Fluorescence
1.4ct G VS1 with Faint Fluorescence
Posted by Ellen

Other Diamond Fluorescence Colors

Rarely diamonds fluoresce another color like yellow or orange. Do not buy them unless the diamond concerned is a fancy color of the same hue as the fluorescence (which will make it more intense). Colorless diamonds with yellow or orange fluoro will appear to be a lower color when seen in light with a UV component. The photos below show how yellow fluorescence enhances the color of a yellow diamond. The photo on the far left shows the yellow diamond in diffuse natural light. The middle and far right photos show the same stone display yellow fluorescence in direct sunlight and under ultraviolet light.

Yellow Diamond FluorescenceYellow Diamond FluorescenceYellow Diamond Fluorescence
Kite Shape Yellow Diamond with Strong Yellow Fluorescence
Posted by davi_el_mejor

Diamond Phosphorescence

When the UV light is turned off, fluorescence ceases instantly, but some rare stones will phosphoresce after exposure. The Wittelsbach-Graff Diamond and The Hope Diamond show intense orange-red phosphorescence. The Hope and The Wittelsbach-Graff both phosphoresce after exposure to shortwave uv light, but they do not exhibit fluorescence during exposure to shortwave or longwave uv light. This unique property adds mystery to these incredible and historical diamonds.

The Hope Diamond
The 31.06ct Wittelsbach-Graff Diamond and The 45.52ct Hope Diamond
Photo by Chip Clark, Smithsonian

People will often choose a fluorescent diamond over a non-fluorescent stone, and many diamond experts actually seek them for this interesting property. An additional bonus is that they may cost less.

In essence, Diamond Fluorescence is generally not an issue. Rather, it is a cool effect and a fun feature, so enjoy!

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