gemstone
Precious Red Coral
Corallium rubrum (Calcium Carbonate, CaCO3)
Hardness: 3.5-4 Mohs; Color: Varies from pale pink to deep oxblood red; Luster: Dull (natural) to Vitreous (polished); Cleavage: None; Structure: Amorphous/Organic branches
- Hardness
- 3
- Color
- Varies from pale pink to deep oxblood red
- Luster
- Dull (natural) to Vitreous (polished)
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Physical properties
Hardness: 3.5-4 Mohs; Color: Varies from pale pink to deep oxblood red; Luster: Dull (natural) to Vitreous (polished); Cleavage: None; Structure: Amorphous/Organic branches
Formation & geological history
Produced by marine polyps in skeletal colonies, typically found in rocky seabeds at depths of 10 to 300 meters, notably in the Mediterranean Sea.
Uses & applications
Primary use in high-end jewelry, beads, cabochons, and decorative carvings. Highly valued as an organic gemstone.
Geological facts
Unlike reef-building corals, precious coral grows very slowly, sometimes only a few millimeters per year. In many cultures, it was historically believed to protect against evil spirits and ensure health.
Field identification & locations
Identify by looking for longitudinal striations along the branches and a lack of air bubbles. Genuine coral will effervesce when touched with an acid like vinegar. Common in the Mediterranean and near Japan.
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