Its name, similarly, combines sard (referencing the ancient Persian city, Sardis, in present-day Turkey, where the red stone was found) with onyx (from the Greek word of the same spelling, which meant “nail or claw.”)
Sard ranges in color from yellowish red to reddish brown, depending how much iron oxide is present. Sard is easily confused with carnelian, another type of chalcedony that is slightly softer and lighter in color.
Sardonyx, like onyx, shows layers of parallel bands—instead of the chaotic, curved bands that compose agate, another type of chalcedony.
The finest examples of sardonyx, which display sharp contrasts between layers, are found in India. Other sources include Brazil, Germany, Czechoslovakia, Madagascar, Uruguay and the United States.
Measuring 6.5 on the Mohs hardness scale, sardonyx is widely available and relatively inexpensive as gems, beads and jewelry. It is often carved into cameos, intaglios and broaches to show the color contrast between layers.
Used as a stone of strength and protection since ancient times, sardonyx is associated with courage, happiness and clear communication. Some believe that placing sardonyx at each corner of a house will grant protection against evil.