This pretty pendant is 1 5/8" in diameter and is made of highly polished 1/8" thick carnelian, a type of onyx. The round pendant has an open center decorated with a ring of silver set with marcasites (cut and faceted steel beads). A sterling bail decorated with more marcasites completes the pendant. There is a 23" sterling silver chain with a substantial link included; the clasp is a lobster-style clasp. Both pendant and clasp are marked "925." This necklace is somewhere between 20 and 40 years old. It is in excellent original condition. It weighs .73 oz.