It is interesting to know that diamonds which look beautiful and sparkling come from the bottom of the earth. There are also the hardest substances on earth and they come in different shapes and sizes. They are form between 120-200 kilometers or 75-120 miles below the earth’s surface. Diamonds are never formed by heating of coal with high temperature and pressure as many presumed. Instead diamonds are made completely of carbon atoms and are formed from the melting of pre-existing rocks in the earth’s upper mantle. Carbon atoms exist in the upper mantle of the earth in large quantities. When temperature changes the carbon atoms are forced downward and deeper into the mantle where they melt when the temperature has reduced. If the conditions of pressure, chemical bonding and mixtures are right, the carbon atoms in the melting rock now bond to form diamond crystals. These diamond crystals take thousand of years to come near the earth surface.
Diamonds are brought to the surface of the earth by volcanic eruptions which occur deep in the earth mantle. In these eruptions, magma travels within the earth mantle with speed passing through the zone where diamonds are formed on it way to the surface of the earth. The force of the movement of the magma breaks rock in the diamond stability zone and the pieces of rocks are carried to the earth’s surface. Diamonds battered and windswept from these eruptive deposits are also found buried at the sedimentary layers of streams and coastlines.