Carnelian

Carnelian is the variety of chalcedony coloured by iron oxide impurities from pale orange through brownish red to almost black. Its darker and harder form, sard, shades into it without a sharp boundary, and the two names are often used interchangeably. Most of the stone sold as carnelian is in fact pale agate that has been heated or dyed to colour it. People have made beads and seals from carnelian since the Neolithic.

Beads and jewellery: bead-making in carnelian goes back to the Neolithic; the Indus Valley Civilization made etched carnelian beads in the 3rd millennium BC. Today it is used for tumbled stones, beads and cabochons. Seals and engraved stones: in Roman times signet rings were made of carnelian, while sard was used for Assyrian cylinder seals and for Egyptian and Phoenician scarabs. History: the seal that Napoleon found during the Egyptian campaign and carried with him for years was also carnelian (Kunz).

It has a hardness of 6.5–7 on the Mohs scale. It scratches glass and steel; a steel knife cannot scratch it. Its specific gravity is 2.58–2.64 g/cm³.

Its best-known localities: Khambhat (Cambay) area, Gujarat, India; Ratnapura, Sabaragamuwa, Sri Lanka; Yanacodo, Peru; Rio Grande do Sul, Brazil; Artigas, Uruguay.

Held to the light, light passes through its thin edges (it is translucent); its colour lies between orange and brownish red, and it is often cloudy or only faintly banded. Its hardness is 6.5–7: it scratches glass, and a steel knife cannot scratch it. A polished surface has a glassy shine; a broken surface is uneven, with no distinct cleavage plane. Heated or dyed agate: most of what is sold as carnelian is a commoner, paler agate or chalcedony. The iron in it turns bright orange-red when heated. Heating is very common, but the seller should say so.

On the “street to diamond” value ladder it sits on step 5 of nine: Ornamental stone. The value of carnelian depends on its colour (a deep, saturated and even orange-red is the most sought after), translucency, cleanliness, and whether the colour is natural or the result of heat treatment. Carnelian is the best-known and generally least expensive variety of chalcedony; most is made into tumbled stones, beads and cabochons. Heated or dyed stones are common and should be disclosed. Old engraved seals and carvings, however, may have artistic and collector value.

It is told that in the East people feared the envious, and that a prayer engraved on a carnelian was believed to protect its wearer from the harm of the envious and of the devil. The popularity of carnelian as a talisman in the Islamic world is traced to the story that the Prophet wore a silver ring set with an engraved carnelian on the little finger of his right hand; the imam Jafar is also said to have declared that all the wishes of whoever wore the stone would be granted. In earlier times carnelian worn at the neck or on a finger was believed to cool the blood and still anger, and the lapidary of King Alfonso X recommends it to people with a weak voice or timid speech, since the warm-coloured stone was thought to give them courage. In Türkiye, some news and crystal-therapy sites claim that carnelian regulates blood circulation, balances low blood pressure, cleanses the kidneys and raises life energy and self-confidence. There is no scientific evidence that carnelian protects against the evil eye, calms anger, regulates blood circulation or balances blood pressure; the iron oxide that colours the stone does not mean that it has such an effect on the body. Blood pressure and kidney problems need a doctor’s supervision, and a stone is no substitute for treatment. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.