Sard is an orange-red to brownish-red form of chalcedony which was used extensively in the ancient world for jewelry, seals, and religious regalia. Like other forms of chalcedony, sard is composed primarily of quartz, chemically known as silicon dioxide. The color comes from iron oxide which seeps into the stone while it is forming, often creating bands of color within the finished rock. Sard is somewhat translucent, and is often marked with white bands or flecks.
In color and composition, sard is essentially identical to carnelian. Some people lump the two stones together, since they are both reddish brown and they are chemically identical. Others, however, prefer to distinguish strongly reddish brown stones as carnelian, and more orange to yellow stones as sard. In either case, if a stone is marketed as “sardium,” it is a form of chalcedony which has been dyed to achieve the desired rich, highly saturated color.
The name probably comes from sered, a Persian word meaning “yellowish red.” Pliny believed that the stone was named for the the city of Sardis, a city in the kingdom of Lydia, located in modern day Turkey. However, the Persian word is the more likely explanation for the name of the stone, especially when one considers that sard was used to make official seals in the Persian world, as well as religious ornaments.
Both men and women wore sard, and numerous examples of Greek and Etruscan jewelry include stunning specimens of ornately carved sard. The stone lends itself very well to carving, and was often used in a carved form. The Egyptians made sacred scarabs from sard and jewelers made sard beads or cameos by carefully carving the richly colored stone. Sard continues to be used in jewelry in both plain and carved form. Large chunks of distinctively colored sard may be cut into cabochons or other large, rounded cuts to show off the intricacy of the color and layers in the stone.
To care for sard jewelry, try to avoid exposing the stone to harsh chemicals and excessive sunlight. Sard can crack or break, so it should be worn carefully and not slammed or bumped into hard surfaces. If the stone becomes chipped or dull, it can be repolished by a jeweler, although it may also be oiled to revive the luster. If the stone is in a setting, check it periodically to ensure that the setting is firm, so that the sard will not slip out.