Carnelian is an orange red to orange brown chalcedony. Most carnelian is heat treated to create a uniform color for jewelry use. Natural carnelian can vary considerably from light tan color to very dark sard color.
Carnelian was a popular stone in Egypt and other early cultures. In ancient Rome it was sometimes cut as a cameo using banded carnelian agate to create beautiful intricate designs.
Gemstones often have an ebb and flow of popularity. But the rich color of carnelian, its ease of working and its ability to take a good polish has made it a perennially favorite gemstone.