These gray clasts breaking up as they flow through the black melt give this piece a great range of contrast and brightness.  The front is polished sterling.  This is from a slice of NWA 13119 and is set in a hypoallergenic, tarnish resistant sterling silver with a pure silver bezel.  The pictured heavy weight sterling silver rounded box chain, 20 inches, 1.8mm, is included.  If you would like a different length let me know at checkout.