This is a perfectly lovely vintage Art Deco era cameo set in sterling silver with marcasites. It can be worn as either a pin or a pendant. It is carved from shell and the frame is unmarked but tests as sterling. The pin back fastens with a safety catch.
It measures about 1 5/8 by 1 inch and it is in very good condition. There are a couple of small stress lines that can be seen if it is held to the light, but these are not cracks or damage.