Seems to be copper, middle isnt plastic more like some kind of stone, it had 2 clips on the back but little brother got to happy an accidently pulled them off.. Some sort of pin maybe?
Probably turquoise, possibly the metal was nickle, which was called "German Silver." Possibly rock hound made, my Dad made stuff like that. Doesn't look Indian made to me. Oops, Native American, doesn't look like it's made by them to me.
I find somewhat similar items with Peking and/or Czech glass, deco, 1920's or 1930's... Those pieces often had brass... But all that is just a bunch of guesses. It would be worth examining the back closely, I would rather expect it to be marked, as its pretty cool.