Sard is a reddish-brown chalcedony, SiO2, much used by the ancients as a gemstone. Pliny the Elder states that it was named from Sardis, in Lydia, where it was first discovered; but the name probably came with the stone from Persia (Pers. sered, yellowish-red). Sard was used for Assyrian cylinder-seals, Egyptian and Phoenician scarabs, and early Greek and Etruscan gems.