Czech black opal clasp

Well, it doesn't really look like a black opal, but that is what the 1940s packaging said it was. It is, however, lovely. The glass centerpiece has a predominately black background with patches of silver foil shot through with red and blue. It is a tiny clasp, perfect for small projects. The centerpiece is 8 mm by 16mm. The clasp measures 28 mm from ring to ring. The centerpiece is set in a hand-made sterling silver box clasp.