In all do honesty, I do not know exactly what kind of the metal they are made from. I am not that smart when it comes to things like that, but I do know that the backs just slide on. I hope this helps a bit and I wish I could have been more helpful.
NOTICE: New information regarding this body jewelry. I just found out that they are sterling silver and they are brand new. I am sorry for any confusion.
Now with all this new information revealed, let's get the final bidding going!!! Well worth your bids!