A small portion of the world's diamonds will have a fluorescent effect, most of the diamond fluorescence is blue, and a tiny portion of the other is Yellow, Red, Green, Orange, Pink, and so on. Diamond fluorescence according to the GIA classification standard in order of None, Faint, Medium, Strong, and Very Strong, respectively, with its initials N, F, M, S, VS.

Generally speaking, weakly fluorescent diamonds are invisible to the naked eye under natural light and can only be seen under ultraviolet light; while strongly fluorescent diamonds can be seen with the naked eye under natural light and ordinary light, and strong fluorescence will make the diamond show a foggy or greasy effect. Given the effect of fluorescence on diamonds, usually, if the diamond can be seen under the naked eye fluorescence reaction, the diamond grader will reduce the color grade of the diamond by 1-2 grades. Too much fluorescence in a diamond can affect the beauty of the diamond, so people usually do not buy diamonds with strong fluorescence.

Table of contents
1. What is fluorescence in diamonds?
2. Why is it important to know about the fluorescence of diamonds?
3. Are all diamonds fluorescent?
4. The difference between fluorescence in laboratory diamonds and natural diamonds
5. what does strong fluorescence do to a diamond?

1. What is fluorescence in diamonds?

Simply put, it is the phenomenon of diamonds fluorescing when illuminated by a violet light (or some other short wavelength light source). The fluorescence of diamonds is mainly related to the impurity N element in the crystal. Due to the presence of the N element, when the crystal is irradiated by a violet light, these higher energies cause the outer electrons of the atoms or ions in the crystal structure to jump, causing the diamond to emit light, i.e. fluorescence.

This type of fluorescent luminescence has the following characteristics: Color: The most common is blue fluorescence, but may also show white, yellow, green, and other colors. Intensity: The intensity of fluorescence can range from Faint to Very Strong. The intensity depends on the amount of trace chemical elements in the diamond. Duration: A diamond's fluorescence usually disappears within seconds after the light source is removed, but a few diamonds can last for several minutes. Effects: Intense fluorescence may affect the color rating of a diamond.

2. Why is it important to know about the fluorescence of diamonds?

Determining Quality: The intensity and color of a diamond's fluorescence can also affect its overall quality. Strong blue fluorescence may affect the color and brilliance of a diamond, thus reducing its value. Conversely, moderate fluorescence can sometimes increase a diamond's attractiveness.
Basis of Identification: The fluorescent properties of diamonds are one of the most important characteristics of diamonds and can help determine whether a diamond is natural or synthetic. Diamonds from different sources will exhibit different levels and colors of fluorescence.
Selling Criteria: Fluorescence is one of the most important factors to consider when evaluating the quality of a diamond. Understanding the characteristics of fluorescence can help to better determine the pricing of a diamond.
Selecting a Diamond: For the buyer, understanding the fluorescence of a diamond can help in selecting the right diamond that best suits one's aesthetic and budget.
  The fluorescence of a diamond is an important technical indicator that is vital to the identification, evaluation, and trading of diamonds, and this knowledge can help to make more informed buying decisions.

3. Are all diamonds fluorescent?

Whether or not a laboratory-synthesized diamond is fluorescent depends on its specific growth and treatment process. Diamonds synthesized by chemical vapor deposition (CVD) or high pressure high temperature (HPHT) may be fluorescent due to the incorporation of certain trace elements during the growth process. The introduction of nitrogen, boron, magnesium, and other elements during the synthesis process may cause the diamonds to fluoresce in different colors such as blue, yellow, and green. If the dopants are removed or altered during the final heat treatment, the fluorescence will be very weak or completely absent.
Most natural diamonds do not fluoresce, and researchers at the GIA Appraisal Institute studied more than 26,000 diamonds that were graded and found that only about 25 to 35 percent of natural diamonds showed some degree of fluorescence when examined under standard long-wave UV lamps.
Other diamonds: materials like synthetic zirconia, which are used to imitate diamonds, also fluoresce.
For any diamond (whether natural or laboratory synthesized), faint fluorescence does not usually affect the aesthetics of the diamond, but very strong fluorescence may affect the value of the diamond by making it appear duller in certain light. The fluorescence of a diamond is usually indicated on the diamond certificate (IGI or GIA), for example, the IGI report usually indicates the fluorescence grade of the diamond in the “Fluorescence” field, which helps buyers to make a more informed purchasing decision.

4. The difference between fluorescence in laboratory diamonds and natural diamonds

Intensity Differences：
The fluorescence intensity of natural diamonds is usually weak, with most diamonds having a fluorescence intensity of less than moderate.
Laboratory diamonds, on the other hand, tend to fluoresce more intensely, up to medium or higher. This is because laboratory diamonds may have activators added during the manufacturing process to increase their fluorescence.
Color Differences：
The fluorescent colors of natural diamonds are mainly concentrated in blue and white, and sometimes yellow or green.
Laboratory diamonds have a wider range of fluorescent colors and may appear in blue, yellow, green, red, and many other colors.
Difference in Duration:
The fluorescence of natural diamonds is usually short-lived, often disappearing within a few seconds.
The fluorescence of laboratory diamonds may last longer.
Differences in Influencing Factors: 
The fluorescence of natural diamonds is influenced by the chemical composition and structure of the diamond itself.
The fluorescence of lab diamonds is influenced more by the type and concentration of activators added during the manufacturing process.
These differences make it possible to use careful observation of a diamond's fluorescent properties as one of the bases for recognizing whether the diamond is a natural or lab diamond.

5. what does strong fluorescence do to a diamond?

Visual Effects: Diamonds exhibit an unnatural blue or white luminescence when exposed to sunlight or ultraviolet light, which can affect the appearance of the diamond.
Hue Shift: Due to the fluorescent effect, a diamond's hue may deviate from its actual color, resulting in distorted or uneven color.
Brightness Imbalance: A diamond that is too bright or white under certain lighting conditions, affects the overall brightness balance of the diamond.
Texture Alteration: Altering the texture of a diamond so that it appears unnatural and subtle, affects the overall aesthetic appeal.

Overall, fluorescence is not always negative; it can sometimes add a hazy or oily look to a diamond, making it appear whiter in natural light. However, strong fluorescence can also cause a diamond to look different in color to the naked eye, which is a factor that should be carefully considered by buyers who are looking for perfection. While mild fluorescence may have little effect on aesthetics, excessive fluorescence should be avoided at all costs, and should therefore be consulted with a professional at the time of purchase.