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.