Carnelian is a variant of the mineral chalcedony, which occurs in many colour varieties, with carnelian being a light yellow to deep orange. Like onyx, the mineral also occurs in coloured bands. Carnelian was one of the first gemstones to be worn by humans, as it is relatively soft and therefore easy to work with. Because the stone occurs in so many different colours, it is a favourite mineral for goldsmiths.
The use of carnelian in jewellery has a long history. More than 4500 years ago, Egyptian craftsmen were already making jewellery set with this precious stone. The Egyptians believed that the stone would protect souls in the afterlife: indeed, the pharaoh Tutankhamun had various pieces of carnelian jewellery in his tomb. The Ancient Romans and Greeks also valued the stone, which they used for signet rings set with intaglio. An intaglio is an engraving technique in which an image is cut into a mineral, which is then visible in the lower layers of the stone. The opaque colour and relative softness of carnelian make it a very suitable gemstone for engraving. The word carnelian comes from the Latin word "carneus", which means fleshy, a reference to the colour of the stone. In the Netherlands, carnelian was very popular in the 19th and early 20th centuries for use in regional jewellery. Relatively large, faceted beads could be cut from carnelian, which were then worn with gold clasps. Carnelian beads were also often rose-cut - i.e. with facets on the top and a flat bottom - and worn in rings, earrings and brooches.
Carnelian can vary in colour from reddish orange to brownish yellow. The different shades of orange/red depend on the amount of iron oxide present in each stone. Carnelian can be uniform in colour, but also occurs with striped layers: these stones are often used to carve cameos. Carnelian is a relatively soft stone, making it easy to cut into various shapes, and is transparent to slightly translucent.
Because chalcedony is found all over the world, carnelian is a relatively cheap gemstone. Unlike many gemstones, carnelian is actually always opaque and therefore its colour affects its quality. Because it is opaque, it is usually cut as cabochon or in rose cut, or used for beads and intaglio. The gemstone comes in different shades of yellow and orange, with deep orange being the most popular. Most of the carnelian found on the market today is treated chalcedony from Brazil or Uruguay, which has been heated to produce the most popular colour, an intense orange.