Diamonds contain different chemical elements that, depending on their concentration, can cause them to emit a glow in the dark. Diamonds can fluoresce in many different colors, such as yellow, red and green, but the most common color is blue. Stones with non-blue fluorescence are extremely rare, with only about 25% to 35% of diamonds exhibiting any degree of fluorescence when exposed to long-wave UV light. Over 95% of these diamonds have a fluorescent blue color.
Rarely do they fluoresce to other colors, such as yellow or green. Fluorescence is not a grading factor like GIA 4C (color, clarity, cut and carat weight), but it is an identifying characteristic. GIA diamond grading reports and diamond records describe the fluorescence of a diamond by its intensity under long-wave UV light (none, weak, medium, strong and very strong). If the fluorescence is Medium, Strong or Very Strong, the color of the fluorescence will be noted.
Some trade professionals think that blue fluorescence can improve the appearance of a diamond, especially in diamonds with color grades I to M. Bluish fluorescence can cause a faint yellowish diamond to appear more colorless under UV light, which is part of natural light. As a result, diamonds with color grades I to N with very strong to medium bluish fluorescence may have a slightly higher price per carat than diamonds with similar color grades that do not fluoresce. The opposite is true for diamonds with higher color grades.
In commerce, diamonds in the D to H color range with bluish fluorescence are often considered less desirable than diamonds of similar grade without fluorescence, because some people believe that bluish fluorescence can cause diamonds to have a hazy or oily appearance. In a recent study, the GIA found that blue fluorescence has little or no impact on transparency, except in extremely rare cases where a diamond (such as the Portuguese diamond) has a light scattering defect. These defects cause haze that can sometimes be intensified with strong fluorescence, thus reducing contrast in the diamond's face-up pattern. However, it's important to note that fluorescence does not cause haze by itself.
In addition, this “overblue” hazy effect occurs in less than 0.2% of fluorescent diamonds subjected to GIA testing. Despite this fact, the association between fluorescence and haze persists and diamonds in the D to H range with very strong fluorescence often sell for less than diamonds that do not fluoresce, even though their color and transparency will most likely not be affected by their fluorescence. These diamonds can turn out to be a good deal for buyers who are aware of this phenomenon. If you're not familiar with the GIA color scale, learn more with the GIA diamond color chart. No, fluorescence does not cause opacity in diamonds.
Fluorescence can increase the pre-existing haze of a diamond caused by light scattering defects, thus reducing contrast in its face-up pattern, but it does not cause haze in and of itself. Because light scattering defects are incredibly rare, most consumers don't have to worry about fluorescence affecting the appearance of a diamond in most lighting situations, even if the diamond has a strong to very strong fluorescence. But this does mean that consumers should look at a diamond in person. Any fluorescence-intensified opacity, if present, will be noticed (for example) in daylight-equivalent illumination. To study the effect of blue fluorescence on the appearance of diamonds, GIA scientists assembled sets of diamonds of color grade E, G, I and K.
The diamonds in each set were as similar as possible except for the intensity of their blue fluorescence. Diamond appraisers, trained professionals and average observers viewed diamonds under controlled conditions to make a judgment on their appearance. It seems that for the average observer - intended to represent the jewelry-buying public - no systematic effects of fluorescence were detected. Overall viewers perceived that deep blue fluorescent diamonds had a better color appearance when viewed at the table and most observers saw no relationship between fluorescence and transparency. Diamond fluorescence is neither good nor bad; some people find fluorescent diamonds beautiful and fascinating while others don't. Now that you know more about diamond fluorescence read on to learn how light affects the appearance of a diamond. No, diamonds don't glow in the dark; they need an external light source to shine.
However there is one specific condition where diamonds can “glow in the dark” due to their impressive abilities: type IIB diamonds tend to appear blue after absorbing high-energy light such as UV light and glow for a short period of time due to phosphorescence - whose color varies from blue to pink and fiery red depending on the diamond. Diamonds glow with black light due to a phenomenon called fluorescence, and approximately 35% of natural diamonds exhibit some degree of this effect due to certain chemical impurities within their composition when exposed to an ultraviolet light source. Fluorescence can be touched but not really explained when looking at diamonds and diamond engagement rings; we have a large selection of premium cut GIA certified diamonds specializing in stones weighing 1.5 carats or more. If a gem doesn't shine in dark light it could fall into the category of natural diamonds that don't fluoresce. If you are considering a diamond with bluish fluorescence look at it under different types of lighting including natural light if you can and compare it to other diamonds of the same color grade and see if you notice any differences. Use a variety of methods such as using a Presidium diamond tester and magnifying the stone to look for characteristics other than diamond formation while most blue diamonds appear to glow blue-green after exposure to ultraviolet rays; one study showed that blue often covers up red phosphorescence and that Hope diamond simply has stronger red sheen than most since neither artificial nor gray faux colored diamond shone at reddish wavelength this characteristic can be used as an identifier for natural stones.
