~ The Effect of Diamond Fluorescence ~
Fluorescence occurs in a third of all gem grade diamonds when they are exposed to the ultraviolet light produced by black lighting or other long-wavelength UV source. The UV light excites electrons in the diamond crystal, which then release this absorbed energy in the form of visible light of faint to very strong intensity. It’s the intensity of this fluorescence that will form the basis for the diamond’s identification and collection at mining sites.
Fluorescence vs. Phosphorescence.
Once the light source is removed, fluorescence is no longer observed. If, in rare situations, light emission continues for a period after the exciting light has been turned off, the phenomenon is called phosphorescence. An example of this is the Hope diamond, whose color changes from blue to red when exposed to UV light then glows red momentarily after the UV light is turned off.
Why do diamonds with Fluorescence cost less?
Recent studies have shown that blue fluorescence in any amount does not impact the face up appearance of a diamond; therefore, it is only the prevalent belief of the diamond traders and the consumers that causes less demand for diamonds with strong fluorescence and this brings the price down. In the 1950s, diamonds with fluorescence were sold at a premium, and were called “blue white” diamonds. Then in the 1970s, the use of black lights in the discos showed the diamonds’ fluorescence and the price of fluorescence diamonds dropped as did the demand for them. The presence and color of fluorescence and its intensity in a diamond are indicated on all GIA and AGS diamond grading reports.
Is there an upside to diamond fluorescence?
Since UV radiation is a component of daylight and is also present in fluorescent lit rooms, diamonds with fluorescence can appear to slightly change color quite often. Fluorescence diamonds that produce a blue reaction are more desirable because the diamond usually appears whiter, or more colorless, under UV light sources.
This is also why it's not a bad idea to get a stronger fluorescence when you buy a I / J or lower color diamond. Blue is the opposite of yellow. In lower color diamonds there is a yellow tint that can easily be seen. However, if you have a diamond with a blue fluorescence, it will offset the the yellow. Virtually making your diamond appear very white (colorless).
Fluorescence diamonds that fluoresce yellow appear even more yellow under some lighting conditions making these diamonds less desirable when you want a colorless look. But it's not a bad thing if you want a yellow diamond, or to even have yellow fluorescence in a vivid yellow diamond.
The diamond certification will tell you whether or not there is fluorescence in the diamond, it will tell you how strong as well as what color. So you always have the information you need.
Helpful Tips when it comes to diamond fluorescence
- Ovoid Fluorescence when ...
Diamonds with a strong or very strong fluorescence are priced slightly lower than other diamonds of the same color grade and clarity grade. The visible effects of diamond fluorescence grades of inert, faint, negligible, and medium, can only be detected by a trained gemologist under very controlled lighting conditions. Blue fluorescence, if strong or very strong, may alter the appearance of a diamond with a high color grade (D-F) in a negative way. For diamonds with very high color grade, D to F grade, strong fluorescence is believed to interfere with the flow of light and make the diamonds appear a little oily or murky. We recommend a grade of None to Faint blue fluorescence in colorless the diamonds with D to F color grades.
- You Want Fluorescence when ...
To a diamond with a color grade of H to M, a moderate amount of blue fluorescence will actually make a diamond more attractive to most people. Moderate or even strong blue fluorescence in a diamond with these color grades actually helps cancel the yellow and the diamond color will appear whiter. For an excellent value in a round diamond with no noticeable color to the unaided eye, look for a near-colorless grade of H-I, choose a diamond with close to an ideal cut proportions, a SI1 clarity, and consider going with a medium to strong blue fluorescence. This diamond will have beautiful color and clarity to the unaided eye and will sparkle in all engagement rings.
When shopping for a diamond, check to see if it has fluorescence. If the diamond has blue fluorescence, it probably won’t be a factor in the diamond’s appearance unless the intensity is strong or greater, and even then rarely does blue fluorescence affect the beauty of a diamond.
Diamonds in the color grade ranges that have more yellow (H and lower) may appear to have less yellow color due to the fluorescence, adding positively to the diamond’s appearance. The diamond with higher color grade will discount a diamond slightly due to the negative effect it can have if there’s any amount of fluorescence, while adding a very slight premium to those in the lower color grade category.