Red agate carnelian gemstoneNatural Carnelian
Carnelian is a brownish red to red-orange variety of chalcedony or cryptocrystalline quartz. Its name is believed to come from a variety of cherry known as kornel. The distinctive red-orange color of carnelian is a result of trace amounts of iron. Sometimes the name Sard is used to refer to the darker colors of carnelian, though there is no clear distinction between carnelian and sard.
Carnelian is one of the oldest known gemstones. It was widely used in ancient Rome to make signet or seal rings for imprinting a seal on letters or important documents (hot wax does not stick to carnelian). Carnelian is one of the twelve gemstones mentioned in the Bible as appearing on the Breastplate of Aaron. It also is one of the birthstones listed in the ancient Arabic, Hebrew and and Roman tables and is a Zodiac birthstone for the sign of Virgo.
Like other chalcedonys, carnelian has a hardness of 6.5 to 7 on the Mohs scale, and a density of 2.58-2.64. It has a refractive index of 1.530-1.540. It ranges from translucent to opaque.
Today carnelian is used for cabochons and beads. It is also carved to produce cameos, intaglios and sculptural pieces. The most important carnelian deposits are found in Brazil, Uruguay, India and Madagascar.
Many carnelians being offered in the market today are actually agates which have been dyed and then heat-treated. But there is a way to identify natural carnelian. The dyed agate will display striping when held against the light, while the natural carnelian will show a cloudy distribution of color. Natural carnelian is increasingly rare.
Since carnelian has such a long history, it is not surprisingly that many legends have become associated with it. Carnelian was regarded as one of the luckiest gems to wear. The proverb is that "No man who wore a carnelian was ever found in a collapsed house or beneath a fallen wall." Carnelian was a talisman of good luck as early as the ancient Babylonians and Greeks. Many Muslims man believe that wearing a carnelian brings peace and happiness to the owner. This belief is attributed to the fact that Mohammed wore a ring set with a carnelian seal. The emperor Napoleon jealously guarded a carnelian seal which he found in an Egyptian campaign and often wore as a watch charm.