Coral is one of several so-called “organic gemstones,” the other main ones being pearls and amber. Made out of calcium carbonate (as are pearls) that’s secreted by organisms known as polyps, coral is mostly found in tropical oceans, where colonies of polyps are jammed together to create reefs.
The coral of most interest to jewelers is called precious or noble coral, Corallium rubrum, which ranges in color from dark red to pale rose and “grows” in branched deposits. Precious coral is harvested almost exclusively in the Mediterranean off the coasts of Italy, France, Spain, Algeria, and Tunisia. Other types or coral are pulled from the waters off Malaysia and Japan, Australia and Africa, and numerous Pacific isles.
Thought by the Romans to protect children, today many people are wondering if coral itself needs to be protected. Coral reefs are among the most threatened ecosystems on the planet, dying off at an alarming rate. Pollution along the coast caused by run-off into the world’s oceans is the biggest killer of coral, followed by damage caused by the fisherman.
Still, the perception that the jewelry industry may also be contributing to the problem makes coral an unpopular material for many people. Indeed, Hawaiian black coral, which is not made of calcium carbonate, is already protected, and movements are afoot to ban the harvesting of red and pink varieties, the ones most common to fine jewelry.
What’s made coral attractive to jewelers for so many centuries has been its seemingly inexhaustible supply; its relative softness, which lends itself to elaborate carvings such as intricate cameos; and the way it can be polished to a glossy, lustrous finish. Coral is often fashioned into round, barrel-shaped, or oblong beads, as well as show-stopping cabochons in necklaces and rings. Sometimes coral is left in its natural state, as when tiny branches are strung together to form a bracelet or pair of earrings.
Like turquoise, coral is a staple of Native American jewelry. Though there’s obviously no coral in the Southwestern United States where the Hopi and Zuni have historically lived, coral was introduced to indigenous peoples by 16th-century Spaniards, who imported the material for sale and trade.
Like turquoise, much of the coral on the market today is artificial, and not just in Naive American jewelry. To spot the real thing, look for white flecks and patches on and inside the gem’s surface. If a blood-red piece of coral has no such irregularities and its price seems too good to be true, then it’s probably synthetic.