Abalone Shell Drop Pendant Necklace Vintage 925 Silver Jewelry

Vintage necklace has drop pendant with two different shaped stones, a square abalone shell with a translucent pale-green oval stone above. Silver backing to abalone is stamped 925. Adjustable chain can be fastened 16-18" long, pendant drop length is 1 3/4", square abalone is 1/2" across. Good pre-owned condition, some toning to metal from age. Note that one of the jump rings connecting the pendant to chain is copper.