Red Coral

Red coral, like all coral used as a gem, is not a mineral but the hard skeleton of a colonial marine animal, precious Mediterranean coral being the red Corallium rubrum, built of calcium carbonate secreted by the living polyps. It is soft, hardness 3 to 4, sensitive to acid and heat, and takes a fine polish. Its most important traditional role is in jyotisha, Indian astrology, where under the names moonga or praval it is the gem of Mars, Mangal, and one of the nine navaratna stones, prescribed to strengthen a weak or afflicted Mars for courage, energy and vitality, a living and documented tradition with its own prescriptive literature.

In the Mediterranean world red coral had a long parallel life as an apotropaic charm, worn against the evil eye and hung on children, a use shown in Renaissance painting. An honest account now notes the conservation cost, since precious-coral harvesting depletes slow-growing colonies. Its metaphysical associations largely restate the Martian character in traditional and modern terms.

Precious coral is Corallium rubrum, an animal that builds a hard red skeleton, and the Mediterranean fishery that harvested it supported an industry rather than a curiosity trade.

The centre was, and remains, Torre del Greco on the Bay of Naples, where coral working became a formal industry in the eighteenth century and where the craft is still practised. The banks off Sciacca in Sicily were discovered in the nineteenth century and worked intensively. Boats dragged weighted wooden crosses hung with netting across the sea floor, a destructive method that broke far more coral than it recovered and that is the main reason the shallow Mediterranean beds are now depleted.

The largest single use was the amulet. Pliny records coral hung on infants for protection, and the practice runs unbroken in Italian folk usage into the modern cornicello, the small red horn worn against the evil eye. Coral beads appear in European portraits of children for exactly this reason, and a coral teething stick was standard nursery equipment for centuries.

The trade also ran far beyond the Mediterranean. Red coral moved east along the caravan routes in quantity, and it is a principal material of Tibetan, Mongolian and Himalayan jewellery, where the red beads set beside turquoise are Mediterranean coral rather than a local product. The same trade carried it into Indian jewellery, where it holds a fixed place among the nine stones of the navaratna.

Precious coral is now regulated, and much of what is sold as coral is dyed substitute material.