Vintage Midcentury Green Beaded Necklace Choker 18"

This is a vintage 18" necklace choker in with green beads. Unmarked. Because of the weight I thought this was possibly stone but after further review, one stone has a scrape on it, leading me to think it is some sort of plastic but I haven't determined what. Please see the picture for the stone I am referring to. Regardless, it's hard to see and this is a really pretty vintage piece. 18" long Condition - see description. Jewels1-92 checked