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[Just a brief note regarding strong red fluorescence in ruby. It is fairly meaningless as a test. Most natural sources (Burma, Vietnam, Ceylon, Kenya, Tanzania, Madagascar) produce rubies that fluoresce strong red under LW/SW UV. It is really only Thai/Cambodian rubies that do not. Again, among the synthetic rubies, most show strong red fluorescence.
When Thai/Cambodian rubies were the majority of the market, their slightly weaker SW fluorescence gave an indication to a skilled gemologist. But that source is today largely extinct.
One area where fluorescence is useful is in identifying heat treatment. Certain heat-treated sapphires and rubies may display a weak to moderate chalky blue to green SW fluorescence. It is often the colorless areas of the stone that fluoresce. This can be extremely subtle and so magnification is often useful for its observation. Take care to protect your eyes, and don''t over-expose the stone, as that radiation creates yellow color centers (these color centers later fade).
Keep in mind also that certain synthetic sapphires show a similar chalky SW fluorescence.
A final note on fluorescence. On occasion, I have seen an unusual chalky yellow SW fluorescence in small patches on Kashmir sapphires. No idea what causes it.
Bottom line: like most tests, fluorescence can be useful in the hands of an expert; for an amateur, it can easily mislead.
Richard W. Hughes
"The price of wisdom is beyond rubies"
Ruby-Sapphire.com]
Can you, please, learn me which phenomenon and/or chemical reaction occurs in ruby that produce this blue fluorescence after heat treatment?
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