Diamond Education
Diamond education is essential to understand the characteristics and quality aspects of diamonds. Through our Diamond education page, we aim to demystify these concepts and explain their influence on buying decisions, with the help of informative articles, guides and videos.
Explanation of Fluorescence Phenomenon
We know that a diamond’s most special characteristic is its ability to reflect the light that enters it, making it sparkle. This can be termed as ‘Radiance’ and is not to be mistaken with Fluorescence which is also an important aspect to be considered in a diamond. Fluorescence, or the lack of it, can impact the overall beauty, and hence the value of a diamond. A diamond with excellent clarity, color and cut, that’s vibrant, bright and full of brilliance - can still be marked less on value due to the presence of fluorescence. What fluorescence does not affect in the least, is a diamond’s durability or hardness.
None, Nil,
Negligible
No fluorescence, no influence on color.
Faint, Slight
Weak fluorescence, not a significant influence on color (barely perceptible).
Medium
Average fluorescence, small influence.
Strong,
Very Strong
Strong fluorescence, substantial color influence.
What is Diamond Fluorescence
and is it important?
Fluorescence refers to the visible light of varying intensity that is emitted when a diamond is exposed to invisible ultraviolet (UV) radiation. This is caused by submicroscopic structures within the diamond. Colorless diamonds usually emit a blue fluorescence. Renowned grading laboratories like the GIA, IGI and HRD clearly indicate the level of diamond fluorescence in their reports, which is why it is important to understand what is diamond fluorescence. For someone wearing a diamond in a typical social setting, fluorescence is very likely to go unnoticed. Only 25% to 30% diamonds graded by the GIA in the past decade have had some degree of fluorescence, and only 10% of those have shown strengths of fluorescence that may impact a diamond’s appearance.
Diamond Fluorescence
good or bad?
Diamonds with Faint or Medium fluorescence can have the appearance of a slight haziness, though not a highly noticeable one. Some experts are of the opinion that diamonds with Strong or Very Strong fluorescence can appear quite hazy or oily, however a miniscule percentage of diamonds are known to exhibit this effect. Fluorescence can make a slightly yellow diamond appear more colorless even in natural daylight; the blue effect and yellow hue cancel each other out, giving the diamond a whiter appearance. This is why diamonds with color grade D-F that have fluorescence are affected by a lower grading and decrease in value, while fluorescent diamonds of color grade I-M are valued higher and sold at a premium.
Impact on Diamond's Appearance
Effect of Fluorescence on Colorless diamonds
Fluorescence does not work in the favor of Colorless diamonds due to their ultra-clean appearance. For diamonds in the D-F range, it is recommended that the diamond certificate should have a Nil or None grading for Fluorescence, as even faint fluorescence will add a tinge of blue to an otherwise white stone.
Effect of Fluorescence on Near Colorless diamonds
When we consider fluorescence in Near Colorless diamonds, less is more. Diamonds in the G-H color scale are benefitted by Faint fluorescence at best. Faint fluorescence can boost the diamond’s appearance by upping one color grade, making a near-colorless diamond appear colorless without the ‘super blue’ look.
Effect of Fluorescence on Faint yellow diamonds
Warmer colors with fluorescence tend to have an extreme rainbow effect. Diamonds in the I-M range may gain from faint to medium fluorescence under certain lighting conditions by getting a color enhancement. Lower the color grade, the stronger is the impact of fluorescence as long as it is blue.
To check and grade fluorescence, diamond graders use a Shortwave and Longwave UV lamp set. This instrument provides the necessary illumination for fluorescence testing, while serving as a miniature darkroom to minimize ambient light. The more fluorescence a diamond has, the stronger the blue light will appear radiating from the diamond when placed inside the UV lamp set. A diamond that has no fluorescence will appear dark and unreflective to the blacklight.
Diamond Fluorescence - Conclusions
Fluorescence of Faint to Medium degree isn’t easily visible in normal, everyday situations. The dreaded blue fluorescence is most perceptible only in dark conditions when a diamond is looked at face-up using a UV light source. When buying a diamond online, the images displayed may not give a correct depiction of fluorescence, so it is recommended to request more up-close images before making a decision.
© 2026 DiamondXE Pvt Ltd. All Rights Reserved
This website uses cookies to ensure you get the best experience on our website. Cookies Policy