Coral
Coral isn't technically a gemstone or even a mineral at all. However it is a natural treasure that was probably known to the ancient pirates because of its association with the sea.
What Is Coral?
Coral can be described (informally and probably inaccurately!) as an "organic stone". It's formed in the sea by many tiny sea creatures called polyps, a whole colony of these goes to form one piece of living coral. When these polyps die - either naturally over time or by being removed from the water - the calcium from their skeletons hardens to form coral rock.Natural coral makes some fascinating and beautiful shapes. Alternatively sections can be cut and polished for use in traditional jewelry such as rings and earrings. Red coral is particularly popular for this, especially in traditional Indian jewelry.
Over-harvesting of coral has led to a lowering of stocks, other environmental issues have either killed off or "bleached" much of the rest. Coral producing countries are increasingly introducing laws to protect coral reefs. This may well result in coral jewelry becoming more expensive to buy over time.