What is Carnelian

Carnelian is a reddish-brown, orange-brown, or yellow-brown variety of Chalcedony. Used in inexpensive jewelry and carved Chinese objects. The color is caused by iron oxide.
The correct name, according to G. F. Herbert Smith, is the word cornelian, having been derived from the Latin cornum (cornel berry) rather than  carnem (flesh)

This carnelian ring stone from 208–209 CE is carved with portraits of the Roman emperor Septimius Severus and his wife Julia Domna, as well as that of their sons Caracalla and Geta. Courtesy: The Metropolitan Museum of Art, NY