This rich colored gemstone is a type of chalcedony quartz that comes in bright red, orangey reds and red-browns. The Carnelian red is obtained from the iron oxide within the stone. The dark brown-red color is often referred to as Sard, although both share the same chemical composition and are derived from Silica with traces of iron oxide. The gemstones vary from translucent to opaque.
The name Carnelian is believed to originate from the Latin word Cornum, for cherry, the color of Carnelian.
Cabochons are the most favoured cuts for the Carnelian since they are at their best when the stones are rounded into a dome and polished
Gemstones purporting to be Carnelian can often be Agates that have been dyed and heat treated. However, differentiation between the two can be achieved by holding the Carnelian up against the light and inspecting it for the tell tale stripes or swirls of the Agate. Genuine carnelians should only show a cloudy spread of color.
Carnelians measure 6.5 to 7 in hardness on the Mohs scale and therefore fairly durable with care.
Historically, Carnelians have been used as talismans to for good fortune and protection against harm. It is reputed that the Emperor Napoleon had a Carnelian and that the Romans used them as signet rings for sealing letters with wax.