This is a large, 3 1/4"x 2 1/16", pierced pin, with clear round, and emerald cut, stones. This brooch is designed for, and looks to be made during, the Art Deco inspired, Roaring Twenties. There are no maker's marks on this fine piece of jewelry. It is missing a few of the smaller round stones, but the larger, emerald cut, centerpiece stones, are all intact.
Item ID: 608