Because of its magnificent color, coral has been one of the most sought-after ornamental minerals since prehistoric times. In Switzerland, objects with coral decorations were found in Celtic graves dating back to the Iron Age. The Ancient Greeks believed it to be the petrified blood of Medusa.
Coral is a calcareous substance secreted by microscopic marine animals known as polyps to form a protective shell or external skeleton. These extend into branch-like forms, colored red by the presence of carotene. Coral can vary in intensity from blood red to pink, although a much-coveted white coral also exists, as does a keratinous black coral, now a protected species. Coral is harvested in warm waters, at depths of up to two hundred meters, after which it is sculpted and polished. Depending on its size it can be transformed into small sculptures, balls, brooches or delicate items of jewelry. Cartier has often used coral, preferably orange-tinted, to create elegant color combinations with emeralds or onyxes. Hardness: 3 to 4. Mediterranean (Italy, Algeria), Indian Ocean, Pacific Ocean (Australia).