All diamonds are formed under immense heat and pressure beneath the earth and are brought to the surface in volcanic eruptions. They are formed between 100 miles underground. Most are found inside a volcanic rock and mined in areas where volcanic activity is still common. Any other diamonds are found loose.

Twenty countries in the world produce diamonds. South Africa is now the fifth largest. Diamonds are made of pure carbon. So is graphite, the stuff that the lead in pencils is made from, but with the carbon atoms arranged differently. Diamond is one of the hardest naturally occurring substances on earth, but graphite is one of the softest with a score of one and a half. The largest known diamond is 2,500 miles across and measures ten billion trillion trillion carats. Found directly above Australia the diamond sits inside the star Lucy.