Corals are ornaments of organic origin. They mainly consist of reefs, atolls, and coral reefs, with multiple forgiveness. However, only the upper ends are used as jewelery stones.

CORAL
Colour: red, pink, white, black, blue
Mohs hardness: 3.0-4.0
Density: 2.6-2.7
Transparency: penetrating, opaque
Fracture: irregular, splintered, brittle.