Precious coral or red coral is the common name given to Corallium rubrum and several related species of marine coral. The distinguishing characteristic of precious corals is their durable and intensely colored red or pink skeleton, which is used for making jewellery.
The hard skeleton of red coral branches is naturally matte, but can be polished to a glassy shine. It exhibits a range of warm reddish pink colors from pale pink to deep red; the word coral is also used to name such colors. Owing to its intense and permanent coloration and glossiness, precious coral skeletons have been harvested since antiquity for decorative use. Coral jewellery has been found in ancient Egyptian and prehistoric European burials, and continues to be made to the present day. It was especially popular during the Victorian age.
Precious coral has relative density of 3.86 and hardness 3.5 on the Mohs scale. Due to its softness and opacity, coral is usually cut en cabochon, or used to make beads.
PRIMARY GEMSTONE: An organic gem cut out of a water plant acting as a natural cleansing agent in the sea. Coral has a hardness of ‘3.5’ to ‘4’ on the Moh’s scale of hardness thus are quite soft. The other physical properties of Corals include a refractive Index of ‘1.486-1.658’ and moderate specific gravity of ‘2.60-2-70’.