Carnelian is a brownish red to orange, translucent to opaque chalcedony variety. The coloring agent is iron. Similar to carnelian is sard, which is generally harder and darker. It is probably named after the color of the kornel cherry because of its color. Its name comes from the Latin word carneus, which means “fleshy” also a reference to its color. The color of carnelian can be enhanced by heating.
In India, when freshly mined, carnelian is often placed in the sun to change its brown tints to red. Most carnelians in the market today are agates which are dyed and then heat-treated. When held against the light, the color variety shows stripes; natural carnelian shows a cloudy distribution of color