This is clearly a one-of-a-kind brooch by an individual artisan and is marked 'SS' for sterling in tiny letters on the back. All the stones are bezel set with a large center cabochon of black onyx. I believe the smaller cabochons are cape amethyst, turquoise, malachite, blue possibly lapis or chrysacolla, yellow jade, rhodocrosite, and coral glass.
This contemporary design is in excellent, original condition and has a secure safety clasp and an applied hook for wearing as a pendant. Size is an amazing 3 1/2 inches across. Make a statement with this unusual piece!