Fluorescence is the emission of visible light by a material when ultraviolet light, x-rays, or other forms of radiation stimulate it.  The term “fluorescence” is derived from the mineral fluorite; which is known for displaying intense fluorescent colors.

What is Diamond Fluorescence?

When diamonds with fluorescence are viewed under UV light, they will most often display a blue color.  Diamonds can fluoresce purple, green, orange, yellow, red, or white.  The fluorescence is often seen in patches and diamonds can still fluoresce after the UV light is turned off which is called phosphorescence.  Diamonds with blue fluorescence will have a yellow-green phosphorescence.  Under x-rays a diamond will usually have a blue-white glow.

Certified diamond reports will list whether or not a diamond has fluorescence under a UV light and the strength of the fluorescence.  Fluorescence is not a grade like cut, clarity, or color it is just a description given to further identify the diamond. The GIA categories for fluorescence strength are none, faint, medium, strong, and very strong.  The AGS categories are negligible, medium, strong, and very strong.

What causes Diamond Fluorescence?

Irregularities in the diamond’s atomic structure cause fluorescence. Although the chemical structure for a diamonds contains only carbon, traces of other elements such as nitrogen, boron, or aluminum can be found.  Nitrogen and aluminum create blue fluorescence, a single nitrogen atom will create yellow fluorescence, and two nitrogen atoms with crystal irregularities from radiation will create green-yellow fluorescence.

What is the difference between UV light and Fluorescent light?

UV lighting fixtures emit UV light and fluorescent lighting fixtures emit visible light.  Even though both lights are similar, fluorescent lights are coated on the inside and absorb the UV light emitting only visible light.

Are diamonds with fluorescence less valuable or less desirable?

Many believe the answer to this question is still up for debate and we say it depends on the diamond’s color and strength of the fluorescence.   Diamonds in the near colorless range with strong fluorescence usually sell at a discount and can make the diamond look oily, hazy, or milky.  On the other hand, fluorescence can work in your favor.  Diamonds with strong blue fluorescence in the I and lower color range will make the diamond look whiter in natural light.

Diamonds are beautiful and should be judged by normal light.  A diamond should be selected under the light source it will be worn in.  Do you know anyone that carries around a UV lamp?  When shopping for a diamond for engagement rings, don’t let the word “fluorescence” deter you from looking at the diamond further.  Like color and clarity if the fluorescence is strong you will notice it regardless of lighting.

diamond fluorescence


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