Some diamonds, known as harzburgitic, are formed from inorganic carbon originally found deep in the Earth's mantle.

Less expensive industrial-grade diamonds, known as bort, with more flaws and poorer color than gems, are used for such purposes.

Instead he finessed the diamond nine, a reasonable play in other circumstances but a clear error with the diamonds known to be on his right.

"The largest diamond known is the Cullinun, mined in South Africa," he went on.

The only red diamond known to exist in the entire world.

On the table, sparkling with a dazzling magnificence, lay the famous chain of diamonds known as the Lamballe necklace!

Two years later, a much larger diamond known as the Star of South Africa was found in the same area, causing a diamond rush.

There are fewer than 12 diamonds known to exist in the world that weigh over 100 carats (20 g) with such strong colour.

A diamond, known as the Abaeté brilliant, was discovered in the river in 1791 whilst a group of men were searching for gold.

Orlov (diamond), a large diamond, sometimes known as the "Orloff"