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About fifty percent of diamonds will glow when
subjected to ultra-violet light. The glow, or fluorescence, results from the interaction
between the light's energy and the atoms in the diamond. About ten percent of diamonds fluoresce strongly enough to make a noticeable difference between the diamond's colour in incandescent light (which is low in ultraviolet) and in fluorescent or sunlight (which are high in ultraviolet) |
| Rough diamonds with different fluorescent colours | ||
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The most common fluorescent colour in diamonds is
blue; others are yellow, green and greenish blue. Very strong blue fluorescence can make a diamond look cloudy or "oily", and yellow fluorescence can make a colourless diamond look more yellow than it really is, both can greatly lower the value of the diamond. Generally, the higher the quality of the diamond, the more strong fluorescence will lower the value. However blue fluorescence can make a lower colour diamond, appear a little whiter than it really is, which can increase the value somewhat. |
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Diamond showing blue fluorescence in ultraviolet light |
