This is a very pretty vintage Art Deco pin set with a square faceted translucent green glass stone made to imitate chrysoprase (also spelled chrysophase). The stone is set in sterling silver and there are pairs of faceted clear glass stones at each corner of the filigree setting. It is marked Sterling on the back, although the stamp is partial and hard to read.
The brooch measures 1 1/4 inches square and it is in good condition. There are some small fleabite chips to the edge of one of the facets on the surface of the stone and some light surface scratches. There are also some small chips to the reverse edge of the stone as can be seen in the last picture. These flaws are not very apparent when worn.