Mineral (Organic Gemstone)

Precious Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Hardness: 3.5 - 4 on Mohs scale; Color: bright red to orange-red; Luster: vitreous to waxy when polished; Crystal structure: Trigonal (amorphous microcrystalline); Specific gravity: 2.6 - 2.7.

Hardness: 3
Color: bright red to orange-red
Luster: vitreous to waxy when polished

Identified April 20, 2026More mineral (organic gemstone) →

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Physical properties

Hardness: 3.5 - 4 on Mohs scale; Color: bright red to orange-red; Luster: vitreous to waxy when polished; Crystal structure: Trigonal (amorphous microcrystalline); Specific gravity: 2.6 - 2.7.

Formation & geological history

Formed by tiny marine polyps in subtropical and tropical waters (caves and crevices). The skeletal remains of the polyps accumulate and harden over centuries into a branching structure.

Uses & applications

Primarily used in jewelry (beads, cabochons, carvings) and by collectors. Historically used in talismans and alternative medicine.

Geological facts

Red coral is an organic gemstone, meaning it is biological in origin. It has been used for jewelry since ancient Egyptian and Roman times, often believed to protect the wearer from evil.

Field identification & locations

Identify by looking for a fine, wood-grain-like texture under a loupe. It often contains small pits or cavities. Avoid pieces that feel like plastic or show dye concentrated in cracks.

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Coral (Precious Coral)

Corallium rubrum (Red Coral), Paracorallium japonicum (Momo Coral), Pleurocorallium elatius (Sardinian Coral), various other species within the Corallidae family. Chemically, it's primarily Calcium Carbonate (CaCO 3 ).

Mineral, Organic Gemstone

Precious Red Coral

Corallium rubrum / Corallium japonicum

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