Thx, I decided to go back to a store full of rings, art deco style, costume, etc...about a year after getting one with an amethyst stone with birthday money. I leave NV for good on Fri back to the FL/GA area and decided to look for onyx for the first time.
I browsed onyx jewelry online and may have seen matching earrings for sale. They were on a site described as "Native" Jewlert, meaning Navaho and/or other SW United States Native Indians. And further research listed 3 black materials the made jewlery from including onyx.
Obsidian is softer than onyx and not really suitable for rings. Most "Black onyx" is dyed agate, but it never needs stabilization. The little ring looks like it was made with a commercially made setting (bezel cup) soldered to the band. Years ago I made a hundred similar rings to sell and give as gifts.