Fluorescence is a common phenomenon found in diamonds that is often described as the ability of a diamond to emit a visible light when exposed to ultraviolet (UV) radiation. It is caused by the presence of certain elements within the diamond's crystal structure, such as nitrogen or vacancies in the crystal lattice.
When a diamond is exposed to UV light, it absorbs the energy from the light and then re-emits it in the form of visible light, which is typically blue. However, the fluorescence can also appear in different colours, such as yellow, green, or even red.
What is Fluorescence in Diamonds?
Fluorescence is a common phenomenon found in diamonds that is often described as the ability of a diamond to emit a visible light when exposed to ultraviolet (UV) radiation. It is caused by the presence of certain elements within the diamond's crystal structure, such as nitrogen or vacancies in the crystal lattice.
When a diamond is exposed to UV light, it absorbs the energy from the light and then re-emits it in the form of visible light, which is typically blue. However, the fluorescence can also appear in different colours, such as yellow, green, or even red.
While some people prefer diamonds with no fluorescence, others find the effect to be desirable, as it can enhance the colour of the diamond and give it a unique character. In the vast majority of cases, the level of fluorescence in a diamond cannot be determined with the naked eye in daylight. It can be identified under long-wave UV light. This is the same blue light the makes white clothes fluoresce under disco lights.
On a GIA diamond grading report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV.
Levels of Fluorescence in Diamonds
GIA grade five levels of fluorescence in diamonds: none, faint, medium, strong, and very strong. Diamonds with no fluorescence have no visible glow under UV light. Faint fluorescence is barely perceptible, while medium fluorescence produces a subtle but noticeable blue or yellow glow. Strong fluorescence results in a more distinct and noticeable colour, while very strong fluorescence produces a strong colour.
Impact on the Appearance of the Diamond
The impact of fluorescence on the appearance of a diamond depends on the level of fluorescence and the lighting conditions in which the diamond is viewed.
According to research conducted by GIA, the vast majority of diamonds are not noticeably affected in appearance by the strength of their fluorescence.
In some cases, fluorescence can enhance the appearance of a diamond, making it appear brighter and whiter. However, there are occasional instances where diamonds with extremely strong fluorescence can appear hazy or oily. It's worth noting that this effect is extremely rare, occurring in less than 0.2% of the fluorescent diamonds that have been submitted to GIA.
Frequency of Fluorescence in Diamonds
The frequency of fluorescence in diamonds is relatively high, with approximately 25% to 35% of diamonds submitted to GIA over the past decade exhibiting some degree of fluorescence.
Impact on the Value of the Diamond
The impact of fluorescence on the value of a diamond is a matter of debate. Some people believe that fluorescence adds value to a diamond because it can enhance the colour of the diamond and make it appear more vibrant, whilst others believe that very high levels of fluorescence detracts from the value of a diamond because it can cause the diamond to appear hazy or oily.
Diamonds with no fluorescence or faint fluorescence are typically more highly valued than those with medium to very strong fluorescence. Some buyers however specifically seek out diamonds with strong fluorescence and in these cases, the value of the diamond may actually increase due to the unique and eye-catching look that the strong fluorescence can provide.
Impact on the Structural Integrity of the Diamond
Fluorescence does not have any impact on the structural integrity of a diamond. It is a naturally occurring phenomenon that does not affect the diamond's durability or overall structural integrity.
Desirability of Fluorescence in Diamonds
The desirability of fluorescence in diamonds is a matter of personal preference. Some people prefer diamonds with no fluorescence, while others prefer diamonds with strong or very strong fluorescence.
In general, diamonds with nil or faint fluorescence are considered more desirable than diamonds with very strong fluorescence because they are less likely to exhibit the uncommon negative effects on the diamond's appearance.
Overall, fluorescence is just one of many factors to consider when evaluating a diamond's quality, and it ultimately comes down to personal preference and the specific characteristics of the diamond in question.
Below are some resources from GIA that have assisted us in preparing this article:
https://4cs.gia.edu/en-us/blog/understanding-diamond-fluorescence/
https://4cs.gia.edu/en-us/blog/fact-checking-diamond-fluorescence-myths-dispelled/