Natural diamonds are formed hundreds of kilometers below the Earth’s surface. The extreme pressure and temperature at the Earth’s interior caused fragments of carbon to crystalize and form into diamond crystals because under these conditions diamond is a more stable form of carbon than graphite. So, over a period of millions of years, carbonaceous deposits slowly crystallize into single-crystal diamonds (gemstones). Incredibly, diamond is the only gemstone made out of just one element (carbon) in its purest form. It is believed that narrow volcanic pipeline paths running down to the Earth’s interior caused transportation of diamonds onto the earth’s surface during violent eruptions. However, natural diamond resources are very limited and are highly concentrated in a small number of locations around the world.