Lab Created Diamonds on White Velvet | Lisa Robin

DIAMOND Proficiency


The fluorescence of diamonds occurs under ultraviolet. Learn how it affects diamonds and their color.


What is Diamond Fluorescence?


The fluorescence of diamonds occurs under ultraviolet (UV) rays from the sun, fluorescent lamps, and other sources. The emitted light can have a variety of colors (often blue in diamonds), intensities (faint to very strong), and patterns of distribution. The fluorescence disappears when not exposed to the light source.

In the diamond trade, strong blue fluorescence can make a light yellow diamond appear colorless when exposed to sunlight. Since blue and yellow are opposite colors, blue fluorescence masks yellow color. Rarely do some diamonds with robust fluorescence appear hazy or oily. A fluorescent diamond submitted to the GIA exhibits this effect in fewer than 0.2% of the cases.

We are here to help
You don't need to be an expert

That’s why we are here to guide you through every step - from understanding what carat, color, cut and clarity mean, to designing the perfect ring.

There are five levels of fluorescence in diamonds, each of which is classified by the GIA as None, Faint, Medium, Strong, or Very Strong. As part of the grading process, master diamonds of different fluorescence grades will be compared to the diamond until a match is found.

Diamond Fluorescence Grading

Diamond fluorescence is graded with descriptive terms that indicate the severity of the fluorescence—the GIA rates diamond fluorescence as either None, Faint, Medium, Strong, or Very Strong. During the grading process, the diamond will be compared to master diamonds of different fluorescence grades, until a match is found.

  • None - The diamond has no fluorescence
  • Faint (Faint Blue) -The diamond has minimal fluorescence
  • Medium (Medium Blue) -The diamond has slightly noticeable fluorescence, and may appear hazy sunlight
  • Strong (Medium Blue) -The diamond has noticeable fluorescence, and will appear hazy in sunlight
  • Very Strong (Very Strong Blue) -The diamond has severely noticeable fluorescence, and will appear very hazy in


Are all diamonds fluorescent?

No, not all diamonds exhibit fluorescence. Only around 30% of diamonds do, which means that finding a diamond without fluorescence for your engagement ring is possible. We suggest opting for diamonds with no fluorescence or minimal fluorescence at most.

Is diamond fluorescence desirable or undesirable?

The desirability of diamond fluorescence depends on the diamond's color grade. In diamonds with high-quality color grades, fluorescence is considered undesirable. When exposed to ultraviolet light, such as sunlight, the diamond may emit a medium blue or strong blue light, resulting in a hazy appearance. However, in lower color grades, the blue light emitted can offset the diamond's yellow tinge. For diamonds with color grades I to M, some degree of fluorescence can be advantageous, although the stone may appear hazy in sunlight. Consider diamonds with color grades between D to F and either None or Faint fluorescence for a bright, clear, and icy-looking diamond.

Oval, Round, and Princess Diamonds on white velvet | Lisa Robin
Diamond Basics
Diamond Guides
Find out which diamond color grades are optimal, which to consider and which to avoid.
Learn More
Lab Grown Round Brilliant Diamond with Tongs | Lisa Robin
Diamond Sources
Lab Grown Diamonds
Learn about the newest entry into the diamond market, how they compare, and what the budget impact is.
Learn More
Multiple Engagement Rings | Lisa Robin
Ring Guides
Learn About Rings
More than just choosing a beautiful design, learn how to select materials, gemstone, and set your budget.
Learn More