How are diamonds formed?
Most diamonds were formed between one and three billion years ago, in one of four ways:
Diamonds are most commonly formed in the Earth's mantle when certain conditions combine to provide the perfect temperature and pressure to form diamonds from carbon. These diamonds are formed 150-200km below the earth’s surface where temperatures average 900-1,300 degrees Celsius and the pressure is around 50,000 times that on the Earth's surface. Explosions beneath the Earth's surface and movements in mantle bring diamonds to the surface where they are mined.