Blue sapphire slowly gives bad effects

What is fluorescence in diamonds?

Fluorescence, what it means, how to recognize it and the advantages and disadvantages of diamonds

Fluorescence is one of the most controversial topics discussed by experts in relation to diamonds. Diamonds that fluoresce contain certain chemical or mineral substances, especially boron, which make them shine under UV light, usually in a blue color. Other color variants also exist, such as yellowish or greenish blue, but are much rarer. This effect is partly visible in the sun; it becomes particularly pronounced when the diamond is directly illuminated with a UV lamp.

Fluorescence affects around a third of all diamonds, although in most cases it is so weak that it cannot be seen from a purely optical point of view. Only in a tenth of all diamonds with fluorescence does it become so evident that the appearance of the diamond changes significantly under UV light.

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Does fluorescence in diamonds have advantages or disadvantages?

In general, diamonds that glow strongly under UV light are a little less popular than those without this effect, with a few exceptions for otherwise yellowish to yellow diamonds. The reason for the, in some cases greatly exaggerated, reservations about fluorescent stones is an accompanying effect of fluorescence, which occurs very rarely, but with some diamonds it causes them to appear milky and matt under UV light. A freak of nature that can affect diamonds completely independently of other criteria such as purity, color or size.
On the other hand, fluorescence, provided that the milky cloud effect does not affect it, also has certain advantages in lower color levels, which are more favorable than the higher color levels towards pure white. A diamond that ranks in the lower range on the color scale, i.e. is very yellowish, appears whiter than it actually is thanks to blue fluorescence. The reason is simple: blue is the complementary color to yellow, so blue and yellow quasi cancel each other out. However, this effect only occurs when UV light is also present; fluorescence does not come into play under artificial light, regardless of the brightness of the light.

How do I recognize fluorinated diamonds before buying?

Fluorescence is a characteristic that, like 4C, is always shown separately on certificates for diamonds. The GIA, for example, distinguishes 5 levels, from none to very strong. Unless otherwise stated, when buying diamonds you can generally assume that they will not have any relevant, strong fluorescence if this is not explicitly mentioned.

Is fluorescence the same as luminescence and phosphorescence?