sedimentary

Red Coral (Precious Coral)

Corallium rubrum (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3.5-4.0 (Mohs); Color: Salmon pink to deep red; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7

Hardness: 3
Color: Salmon pink to deep red
Luster: Vitreous to dull

Identified April 20, 2026More sedimentary →

Explore Red Coral (Precious Coral) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 3.5-4.0 (Mohs); Color: Salmon pink to deep red; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7

Formation & geological history

Formed by marine polyps that secrete calcium carbonate to build their skeletons. Over centuries, these secretions accumulate into branch-like structures in subtropical/tropical marine environments.

Uses & applications

Primarily used in fine jewelry (necklaces, beads, cabochons), carvings, and as a collectible gemstone.

Geological facts

Natural red coral has been harvested and traded since ancient times. It is an organic gemstone, meaning it is derived from living organisms rather than geological processes alone.

Field identification & locations

Identify by looking for faint wood-grain patterns or 'growth rings' on the surface of beads. Beware of dyed plastic or glass imitations; real coral may react with weak acids (effervesce).