organic
Coral
- Also known as
- precious coralred coralblack coral
- Crystal system
- trigonal
- Hardness
- 3–4 on the Mohs scale
- Lustre
- waxy
- Colour
- Red, pink, white, black, blue
- Where it forms
- The skeleton of a colonial marine animal. Precious red coral is calcite deposited by Corallium species over decades — the colonies grow at a few millimetres a year and take decades to reach harvestable size.
- Chiefly from
- the MediterraneanJapanTaiwanHawaii
Why it is that colour
Carotenoid pigments incorporated by the animal. Black coral is a protein rather than a carbonate, and blue coral gets its colour from iron salts.
Safety
Safe to handle. Much red coral on the market is dyed, bleached or reconstituted, and some is dyed bamboo coral or dyed sponge.
Where it comes from
Listed on CITES Appendix III for Corallium species, with several coral genera more strictly listed, so international trade is regulated. Beyond that it is genuinely difficult. Mediterranean red coral populations have been depleted by centuries of harvesting and colonies are now smaller and younger than historic ones. Black coral is slow-growing to an extreme degree — some colonies have been dated at over four thousand years old — and is protected in many jurisdictions. Buying antique or reclaimed coral avoids new harvesting; buying new material generally does not.
Historical use
Traded from the Mediterranean to India and Tibet for two thousand years, and one of the few European goods with a reliable market in Asia. Torre del Greco near Naples has been the centre of the working trade since the eighteenth century.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
One of the oldest protective amulets in the Mediterranean world. Roman children wore coral against harm, and the practice continues in Italian folk tradition through the cornicello. Ovid gives it an origin myth involving Medusa. Its use in Tibetan, Indian and Native American traditions is also long-established and independent.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
Coral is an animal skeleton, and the conservation case against buying it is stronger than for anything else in this collection. Precious coral colonies grow at a few millimetres a year, are slow to recover from harvesting, and are taken from habitats that support a great deal else. Deep-sea black coral colonies have been radiocarbon-dated at over four thousand years old — individual organisms older than most of the traditions that value them.
This is the mineral-kingdom equivalent of the wildcrafting problem: a material whose symbolic value comes from a tradition that harvested it locally and slowly, meeting a global market that does neither.
Identity checked against IMA-CNMNC master list, June 2025.