Intaglio tourmaline Libra Signet ring

Intaglio tourmaline Libra Signet ring.
Libra zodiac ring STERLING Intaglio natural(?) tourmaline Signet ring purchased at a antique store in the panhandle 15-something years ago. The tester cannot determine stone treatments or if it is lab-created, I was visiting FL in October which just happened to be my b-day month. I remember I was hesitant about the price but now, year’s later I’m glad I followed through with the purchase. It comes out the month of October.