What is fluorescence, exactly?

What is fluorescence, exactly?

If traces of the mineral boron are present in the earth during the crystallization process, a diamond will become fluorescent. When diamonds are exposed to invisible ultraviolet (UV) light, they produce fluorescence, which is visible light. Approximately one-third of all diamonds glow under ultraviolet light, fluorescence diamonds are visible under UV light in darkness.

Fluorescence diamonds will glow or radiate in different colors like blue, yellow, green, or even in red color. Fluorescence on a GIA diamond grading report refers to the strength, or intensity, of the diamonds reaction to long-wave UV. Fluorescence can be found in approximately 30% of all diamonds.

The GIA classifies diamond fluorescence into five levels:

  • 1. None - When the diamond is exposed to UV light, it does not emit a soft, blue glow. There are no trace components in the diamond that generate fluorescence. None fluorescence diamonds are the most expensive and highly desired. Glorious Diamonds always recommend to buy non fluorescent as an investment or real value of your money.
  • 2. Faint – A diamond is exposed under UV light, it emits a slight soft, blow glow. Minor trace elements in the diamond cause fluorescence, known as Faint fluorescent. In fact, the slight fluorescence can make the diamond appear more white. Its 3% - 5% cheaper than Non fluorescent diamonds. They are less likely to have any great visual difference in the diamond.
  • 3. Medium - When exposed to UV light, a diamond emits a light blue glow. Diamonds with Medium Fluorescence will usually make a diamond appear hazy and may even make the diamond appear whiter in color. It has the ability to improve the color of lower grades such as J, K, or L. Medium fluorescence is an excellent value because of 5% - 10% lowers the price.
  • 4. Strong – Strong fluorescence diamond will look a little hazy, cloudy or milky. It may even make the diamond looks a little whiter in lower color. Under a UV light, a diamond with strong fluorescence can have a strong blue color. Strong fluorescence has been considered as a 10% -15% discounted rate in the Jewelry industry. It is the best choice for them who wish to buy better color in low-priced. The World’s famous Blue Diamond – renowned Hope Diamond, infect glows a Strong red fluorescent.
  • 5. Very Strong - When exposed to UV light, the diamond emits a very bright blue glow. The appearance of the diamond may be affected. Strong fluorescence can cause a diamond to appear gray, hazy, milky or cloudy. Under a black light, these diamonds shine brightly. They look spectacular and awesome in the dark, but they will most likely make a high clarity (such as VVS or VS) look foggy, cloudy, milky, and dull. Strong fluorescents diamonds can improve a diamond's color. The best part of strong fluorescents diamonds are 10% - 20% cheaper in price.
Fluorescence Things to Consider
None Excellent

D-E Color - Good, 3-6% discount on the price.

F-G Color - Very Good, 2-3% discount on the price.

H and Above - Excellent, 0-2% discount on the price.


D-E Color - Good, 6-8% discount on the price

F-G Color - Very Good, 2-5% discount on the price.

H and Above - Excellent, 0-2% discount on the price.


D-E Color - Fair to Good, 12-18% discount on the price.

F-G Color - Good to Very Good, 8-12% discount on the price.

H and Above - Very Good to Excellent, 4-10% discount on the price

Very Strong

D-E Color - Poor to Good, 15-20% discount on the price.

F-G Color - Fair to Very Good, 10-15% discount on the price.

H and Above - Very Good to Excellent, 5-11% discount on the price.

GIA Fluorescence Reference Link


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