You searched for: “a diamond”
diamonds, a diamond
These are the hardest and most lustrous gems because they retain their brilliance and polish for many generations.
They are a form of carbon that has been crystallized under great pressure and very high temperatures.
The two major sources for diamonds are South Africa and Australia.
"In 1695, two scientists obtained a diamond from a rich patron and heated it by using a lens to focus light on it. The diamond disappeared. Diamond is made of carbon, and it burns just as coal will when it is heated strongly enough."