Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black. The color of chalcedony sold commercially is often enhanced by dyeing or heating. The name chalcedony comes from the Latin chalcedonius (alternatively spelled calchedonius) and is probably derived from the town of Chalcedon in Asia Minor.
Chalcedony occurs in a wide range of varieties. Many semi-precious gemstones are in fact forms of chalcedony. The more notable varieties of chalcedony like Agate is a variety of chalcedony characterized by either transparency or color patterns, such as multi-colored curved or angular banding. Carnelian (also spelled cornelian) is a clear-to-translucent reddish-brown variety of chalcedony. Chrysoprase (also spelled chrysophrase) is a green variety of chalcedony, which has been colored by nickel oxide. Heliotrope is a green variety of chalcedony, containing red inclusions of iron oxide that resemble drops of blood, giving heliotrope its alternative name of bloodstone. Moss agate contains green filament-like inclusions, giving it the superficial appearance of moss or blue cheese. Onyx is a variant of agate with black and white banding. Similarly, agate with brown, orange, red and white banding is known as sardonyx.