I have these pieces of jewelry from a bulk auction purchase of vintage silver jewelry. The black onyx may be handmade silver, but I am not sure. Nothing seems to have any markings. If you’ve got yourself a soldering gun you have some cheap vintage silver and onyx earrings. Cannot guarantee though and no returns if not. The tarnishing does look like silver tarnishing to me though. Hoping for you it is. Free shipping in lower 48 states.
eBay