925 Sterling Silver Black Onyx Brooch Marcasite Vintage Style Pin Art Deco Large Very good condition! Some light markings and tarnishing on the silver. Gorgeous large sterling silver pin with large black onyx stone surrounded by marcasite stones. Oval/rectangle shape. Art deco design. Stamped 925 on the backside. Not signed. May be vintage. Makes a great gift! 2" x 1.25" FOLLOW TRIXY XCHANGE! Please check out my vintage and funky jewelry!!