Fluorescence in diamonds refers to the phenomenon where a diamond emits a visible light when exposed to ultraviolet (UV) rays. This visible light is called fluorescence and can vary in color, intensity, and duration. Fluorescence can occur in various colors such as blue, yellow, orange, green and red, but the most common color is blue. About 1/3 of diamonds have some level of fluorescence.
Why does it occur? The fluorescence in diamonds is caused by the presence of certain trace elements, such as boron or nitrogen, in the diamond's crystal structure. The intensity of fluorescence is measured on a scale from "None" to "Very Strong", and can range from invisible to the human eye to a very strong visible light.
Fluorescence can affect the appearance of a diamond and can be seen as a positive or negative attribute depending on the individual diamond and the personal preference of the buyer. In general, diamonds with "None" or "Faint" fluorescence are considered to have the least impact on the diamond's appearance. Diamonds with "Medium" or "Strong" fluorescence may have a slight visible effect, such as a hazy or oily appearance, in low lighting conditions. On the other hand, if fluorescence is blue, it can counteract the yellow tint in a diamond and actually make it appear whiter and brighter, especially in sunlight or UV light. According to a GIA study conducted, the impact of fluorescence is not noticeable to the average observer.
The fluorescence of a diamond does not affect the diamond's durability or rarity. However, it is worth noting that some people believe that diamonds with fluorescence are less valuable than those without and diamonds with strong or medium fluorescence are traded at discounted prices relative to diamonds without within the industry and trade. So if you’re ever in a store and a jeweler presents you with two diamonds with the only difference being between the level of fluorescence you should expect a cheaper price for the diamond with fluorescence.
