Diamond Fluorescence Chart Explained
Understanding Fluorescence Grading
Diamond fluorescence is graded according to the strength of the glow a diamond produces when exposed to ultraviolet light. Laboratories such as the Gemological Institute of America evaluate this characteristic and record it on the diamond’s grading report.
Rather than measuring color tint like the diamond color scale, fluorescence grading measures the intensity of the diamond’s reaction to UV light. The result is described using a series of standardized categories.
The Five Fluorescence Grades
Most grading laboratories describe fluorescence using five levels: None, Faint, Medium, Strong, and Very Strong. These levels indicate how visible the glow becomes under ultraviolet light.
Diamonds with no fluorescence do not emit a visible glow under UV exposure. Faint fluorescence produces a very subtle reaction that is often difficult to notice. Medium fluorescence becomes easier to observe under UV light, while strong and very strong fluorescence create a more noticeable glow.
How Jewelers Evaluate Fluorescence
Fluorescence is evaluated in a dark environment using ultraviolet light sources. Gemologists observe the color and intensity of the glow and compare the reaction to standardized grading references.
The most common fluorescence color in diamonds is blue. While other colors occasionally appear, blue fluorescence is by far the most frequently recorded on diamond reports.
What the Chart Means for Buyers
For most buyers, fluorescence grades are simply another piece of information on the diamond report. Many diamonds with faint or medium fluorescence appear completely normal in everyday viewing conditions.
Because the effect is primarily visible under ultraviolet light, the fluorescence chart helps explain a characteristic that may otherwise remain invisible in typical lighting environments.
Related Diamond Guides
• What is Diamond Fluorescence
• Is Diamond Fluorescence Good or Bad
• Strong Blue Fluorescence in Diamonds
• Does Fluorescence Affect Diamond Value
• When Fluorescence is Bad
Final Thoughts
The diamond fluorescence chart provides a way to classify how strongly a diamond reacts to ultraviolet light. From none to very strong, these categories help gemologists describe a feature that occurs naturally in many diamonds.
Understanding the fluorescence scale helps buyers interpret grading reports and place this characteristic in context alongside the other qualities of a diamond.