Why are diamonds so small?

Most gem-quality diamonds found are about the size of a vegetable, the pea.

The largest diamond found to date is the Cullinan Diamond, a mighty excess of 3,000 carats: it fit into the palm of a grown man's hand. It was found in 1906.

Larger gem-quality diamonds are found, but they are rare.

The process of forming diamonds occurs far below the earth's surface, deep within the earth's mantle. Why the diamonds formed there are 'small' is a mystery only Mother Nature can answer.