A Brief History
Diamond is the hardest natural substance on earth, but if placed in an oven at 1405 degrees Fahrenheit
(763 degrees Celsius), it will vanish. Only a small amount of carbon dioxide will have been released.
Diamonds are formed over a period of a billion or more years deep within the earth's crust - about 90
miles (150km) below the surface - and are pushed to the surface by volcanoes. Most diamonds are found
in volcanic rock, called Kimberlite, or in the sea, having been carried away by rivers after they were
pushed to the surface. A diamond is 58 times harder than the next hardest mineral on earth, corundum,
from which rubies and sapphires are formed.
It was only during the 15th century when it was discovered that the only way to cut diamonds was with
other diamonds. Still, diamonds are brittle; if hit hard with a hammer, they will shatter.
Not all diamonds are white. Impurities lend diamonds a hue of blue, red, orange, yellow, green and even
black. A green diamond is the rarest. Diamond, however, is not the rarest gemstone. That title goes to
a pure red ruby. Diamonds actually are found in fair abundance; thousands are mined every year. 80% of
them are not suitable for jewelry and are used in industry. The remainder, of higher clarity, are cut
for the jewelry trade and end up in jewelry stores.