Carnelian is a brownish-red mineral commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder. Carnelian (also spelled cornelian) is a brownish-red mineral which is commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder and darker (the difference is not rigidly defined, and the two names are often used interchangeably).
It is also carved to produce cameos, intaglios and other sculptures. The most important carnelian deposits are found in Brazil, Uruguay, India and Madagascar. Many carnelian gemstones being offered for sale on the market today are actually agate gemstones that have been dyed and then heat-treated.
The Gemstone Carnelian. Carnelian is the red, orange, or amber variety of Chalcedony. Though often a solid color, it may also be banded, in which case it would be jointly classified as both Agate and Carnelian. Carnelian is an ancient gemstone, having been used as gem material since antiquity. Carnelian is one of the birthstones listed in the ancient Arabic, Hebrew, Italian and Roman tables and is a Zodiac birthstone for the signs of Leo and Virgo. Carnelian is a form of chalcedony, a member of the quartz family and most Carnelian is heat treated today to enhance the reddish brown color.