Judith Jack "Mini Octagons" Sterling Silver, Chalcedony, and Marcasite Pendant Necklace, 18" An octagonal pendant and geometric details lend contemporary appeal to the timeless beauty of the Chalcedony and Marcasite in this Judith Jack necklace. Box chain with lobster-claw clasp Crafted in .925 sterling silver The natural properties and composition of mined gemstones define the unique beauty of each piece. The image may show slight differences to the actual stone in color and texture. Imported