Fluorescence occurs in some diamonds when they are exposed to the concentrated radiation of a UV lamp. Submicroscopic structures in the diamonds cause them to emit a visible light, a fluorescence, which is commonly blue in colour.
Some trade professionals think blue fluorescence enhances a diamond's appearance, especially in diamonds with I to M color grades.
Fluorescence is caused by the presence of nitrogen as a trace element in your diamond. Three nitrogen atoms in lattice position in the crystal structure will commonly cause blue fluorescence. Sometimes, the blue is strong and sometimes the blue is faint.
You will see a glow in 30% of diamonds under UV light. 99% of the time, the glow is blue, but on rare occasions, diamonds glow white, yellow, green, or even red in color.
A fake diamond, on the other hand, will almost never look blue under a black or UV light. This is not the most reliable test for those who would like to know the true status of their diamond.
Strong: Diamonds with Strong fluorescence emit a substantial and intense blue hue under UV light, and can cause a diamond to appear very cloudy, milky, or hazy to the naked eye.
You could get fortunate with strong blue fluorescence. People assume it is a super negative factor and avoid it, but it is not bad in H and low-color diamonds. It can help them look much whiter than their color since blue complements yellow. But, it can be somewhat negative in D- G color diamonds.
In most cases, diamonds fluoresce blue. This cancels out the slightly yellowish color in most diamonds, resulting in a whiter appearance in sunlight. In artificial light, there's little UV intensity more than a few inches from the light source.
The blue nuance occurs in diamonds that are grown through the HPHT (high pressure high temperature) process. Luckily, not all HPHT diamonds have it. During the HPHT process, lab diamonds are sometimes exposed to boron, which speeds up the diamond growth process. Boron impurities are what cause the diamond to turn blue.
Blue diamonds are Type IIb diamonds, which are extremely rare and valued very high. Most blue diamonds are rare, but blue diamonds with very high color intensity that display a deep blue color are the rarest. Of course large stones are even harder to come by and much pricier.
In most cases fluorescence is simply an identifying characteristic and not a performance characteristic, and is therefore NEITHER good nor bad. In some cases, strong or very strong fluorescence can make a diamond appear cloudy, diminishing its transparency and eye appeal.
However, Faint fluorescence is often recommended for buyers of lower color grades because it can help to slightly offset some of the color saturation associated with those diamonds (specifically when they are exposed to natural sunlight).
#2 Cut Quality: Better Light Return = Whiter Appearance
In essence, when light enters a well cut diamond, the facets light up to create brilliance that helps mask the diamond's body color. In a badly cut diamond with steep/deep proportions, the body color would show up more due to light leakage.
Grading Fluorescence
In particular, we recommend fluorescence of “none” and “faint” because we believe your diamond should look beautiful in all lighting conditions and these two grades are least affected by fluorescence.
The effect on price varies depending on the degree of fluorescence, diamond color, and clarity. For example, according to the chart, an E color diamond of VS1 clarity and Strong Fluorescence will tend to sell for 3-5% less than a like diamond with no fluorescence.
Here's the good news: When it comes to VS1 vs VV2 diamonds, the differences between the two are very small. Diamonds that are graded as VVS2 (part of that Very, Very Slight Included range) have very minor flaws (called inclusions) that are extremely small, but are slightly more visible under magnification than VVS1.
Red diamonds are the rarest of the colored diamonds, with only 20-30 existing in the entire world. They get their beautiful red color from a rare process during their formation, which changes the crystal structure of the diamond and causes light to pass through it differently than colorless diamonds.
The Black Light Test
This means their color may be altered when placed under specific types of lighting, such as a black light. Place your diamond underneath an ultraviolet or black light. The stone's fluorescence should make the stone appear blue or emit a bluish-color. Fake diamonds will not change colors.
For example, your diamond may have inclusions clustered together in the same area, making the stone appear milky or foggy. Diamond fluorescence may also be the culprit. Some diamonds may have strong fluorescence that can give off a milky hue and reduce the value of the diamond.
The way that diamonds reflect light is unique: the inside of a real diamond should sparkle gray and white while the outside should reflect a rainbow of colors onto other surfaces. A fake diamond, on the other hand, will have rainbow colors that you can see inside the diamond as well.
Named in 1821 in honour of Carl Wilhelm Scheele, scheelite is a primary tungsten ore mineral that displays a distinct blue fluorescence. Miners and geologists would often use this to their advantage in the search by using a UV light at night time to locate the tungsten.
A wide array of fluorophores has been developed for investigations using excitation wavelengths spanning the blue (420-500 nanometers) wavelength region.
Because diamonds reflect white light, colorless diamonds produce the best sparkle and fire. In fact, the more color a diamond has, the less likely it is to reflect white light. And as a result, will produce less sparkle. A D-color diamond is the highest quality, and will offer the greatest sparkle.