What is diamond fluorescence? When diamonds are placed under an ultraviolet light, they emit a soft, colorful glow. A little less than one-third of diamonds fluoresce this way. For a near colorless diamond, is this fluorescence good or bad?

Near Colorless Diamond | Diamond Fluorescence | K. Rosengart

Fluorescence: Defect or Advantage?

The best answer is that it depends. Fluorescence is understood as a defect, so colorless fluorescent diamonds (grade D-F) are often sold at a discount. On the other hand, fluorescence is most often blue in hue. Since this complements the slight yellow hue many diamonds have, it can make grade I-M diamonds appear whiter than they are. These diamonds are often sold at a premium.

In this way, diamond fluorescence as “good” or “bad” is entirely contextual. Generally, it's one of the last factors you'll consider when assessing the quality of a diamond. Because diamond fluorescence is so subtle, it likely won't impact the look of the diamond in way that you can tell. The eye test of whether you like the diamond still surpasses the importance of fluorescence.

Understanding Grades and Ratings

The ratings for fluorescence are as follows: Very Strong, Strong, Medium, Faint, and None. The color grades of diamonds range from D to Z.

If you have a D color diamond, this means it's a colorless diamond. A strong fluorescence can make it appear very slightly hazy even under normal light. If you have a grade M color diamond, that means it has a slight yellowish hue. This is why blue fluorescence offsets the slight yellow in order to make the diamond appear more dazzling.

Guidance on Diamond Fluorescence

Understanding this, the best guidance is that grade D-F color diamonds that have a strong or very strong fluorescence should be avoided unless getting them at a very good price.

Grade G-H color diamonds should only be avoided if the fluorescence is rated Very Strong.

For Grade I-M color diamonds, the fluorescence can actually be an advantage that creates a near colorless diamond in terms of how we perceive it. Anything Grade I-M that's Medium or higher in fluorescence is usually perceived as an advantage.

If you need more information or need help selecting the perfect diamonds, contact the experts at K. Rosengart.