Rare Vintage Dioptase Druzy Silver Ring Size 9

Rare Vintage Dioptase Druzy Silver Ring Size 9. I do not know if this ring is sterling or sterling plated. It has markings they are too small to see. It has never turned or tarnished in the 30 years I've had it. Rare raised raw stone in thin band setting. Gorgeous! You will not find another made like this! Not sure of exact age but it was given to me by my grandmother 30 years ago out of her old jewelry.