FMF - Friends of Minerals Forum, discussion and message board

[Tom Mazanec]

Gemstones of the World Walter Schumann 5th ed. page 101
It says that synthetic, in contrast to natural rubies, can be recognized by the fact that they transmit shortwave UV.
Why? Or rather, how? Synthetic and natural ruby are the same chemical compound, aluminum oxide with traces of chromium. How can one transmit light the other can't?

[rgangue]

Many natural rubies are UV reactive so I'm not sure how this helps with ID. I have both natural and synthetic that react strongly to UV.

[Riccardo Modanesi]

Hi to everybody!
Pay attention: synthetic rubies are nowadays made in such a similar way to natural processes, that it's sometimes very difficult to distinguish them from natural stones! Ramaura syntheses, hydrothermal syntheses etc. are good examples! Some of them require a very careful analysis and UV-Light alone is not sufficient at all to make a correct diagnosis.
Greetings from Italy by Riccardo.