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Fluorescent opal?

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Apr 17, 2002
Is it unusual for opals to fluoresce?

My mother recently gave me a lovely necklace that belonged to my grandmother. It has a row of 9 little pear-shaped rubies and a scattering of tiny full-cut diamonds (also 9 of them), but mostly it''s an opal necklace. 43 small pear-shaped opals, very fiery, mostly blues and greens. The sort of opals you see in Edwardian jewelry. I''m guessing the necklace is from the 1950s.

I was checking it with my little fluorescent flashlight out of curiosity to see whether the diamonds had fluorescence. About half of them have medium or strong blue; the rest don''t seem to have any. I was interested, but not surprised, to see that all the rubies lit up bright red under the blacklight. What surprised me was that the opals seemed to fluoresce blue-green, too.

At first I thought they were just reflecting the purplish blacklight of the flashlight. But when I turned it off in the dark after holding the blacklight close to it for a while, the fluorecent diamonds went on glowing for a few moments, as flourescent diamonds do--and so did the opals. (The rubies, on the other hand, were completely dark as soon as the light went off.)

Is this common behavior for opals? Are they often fluorescent, and do they often go on glowing after the blacklight''s gone?

The Joker

Oct 25, 2003
Fluorescence: The emission of radiation (usually visible light) when a substance is irradiated by higher-energy rediation such as ultra-violet light.

Phosphorescence: The continuation of fluorescence after the activating radiation is turned off.

Source:"Rocks and Minerals" by O''Donoghue

I have seen a lot of Fluorescent Opal from the Virgin Valley of Nevada area, but I have never checked to see if it is Phosphorescent.



Jan 15, 2003
Apparently American opals commonly have yellow-green fluor, and Aus opal is either inert or shows blue-white fluor with green fluor is thought to be due to uranium minerals as inclusions...

Got this info from "Fluorescence" by Robbins, p.171....learn somthing every day!
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