Hi

I believe I have exactly the same stone (size and cut) mounted in a 22 caret Gold ring, the style of the ring is late 1800's early 1900's.

This ring was given to my Mother in Law (my wife is Latvian) by and old lady in Latvia (Former USSR) Interestingly when the Item was purchased originally Latvia would have been independent but with strong trade links with Russia.
The old lady told my mother in law that she was given the ring in around 1900.

The ring is hallmarked.

The gem appears purple in artificial light and light blue in day light

How can I find out more about this stone and be sure its not a synthetic?

Thanks Richard