Diamond Formation

The word "Diamond" comes from the greek word "Adamas", which means indestructible. It is the only gem known to man that is made of a single element, Carbon, besides graphite. Diamond is completely made of Carbon atoms (Chemical Composition - 'C') crystallized in a cubic (isometric) arrangement. Diamond is the hardest substance on Earth. Diamond crystallizes in the isometric (cubic) system, and regularly forms cubes and octahedral.

Diamond form between 120-200 kms or 75-120 miles below the earth’s surface where we have extremely high temperature and pressures. According to geologists the first delivery of diamonds was somewhere around 2.5 billions years ago and most recent was 45 millions years ago. Large diamonds particularly large diamonds with flaws are extremely rare. The flawless diamonds are very valuable as gemstones.

Types of diamond deposits

Primary deposits
Diamondiferous pipes, which are ‘pipes’ of mineral-rich volcanic rock containing diamonds, are known as primary deposits.

Diamondiferous pipes are the solidified cores of kimberlite or lamproite volcanoes.

Secondary deposits
Deposits that contain diamonds which have traveled some distance from their original source are referred to as secondary deposits.

The diamonds that are now found in Namibia, for example, have traveled over 1,000 miles from their original source in southern Africa, transported by the Orange River.
Kimberlite, lamproite and komatiite are the only types of rock known to have transported diamonds from the Earth’s interior up to the surface in significant quantities.

According to science, the carbon that makes diamonds comes from the melting of pre-existing rocks in the Earth's upper mantle. There is an abundance of carbon atoms in the mantle. Temperature changes in the upper mantle forces the carbon atoms to go deeper where it melts and finally becomes new rock, when the temperature reduces. If other conditions like pressure and chemistry is right then the carbon atoms in the melting crystal rock bond to build diamond crystals. There is no guarantee that these carbon atoms will turn into diamonds. If the temperature rises or the pressure drops then the diamond crystals may melt partially or totally dissolve. Even if they do form, it takes thousands of years for those diamonds to come anywhere near the surface.

It is interesting to note that "synthetic diamond" is the form of diamond predominantly used in industry. The process allows the removal of impurities and produces a product with consistent physical properties; most of the carbon comes from graphite. Synthetic diamond accounts for the majority of industrial diamond consumption.

Because it is the hardest substance known, diamond will cut through any material. Consequently, it is used as an abrasive and in cutting and grinding applications. Industrial diamonds are embedded in large steel drill bits to drill into rock for wells to find water, oil, and natural gas. It is also important in the manufacture of machinery for drilling and cutting metal machine parts.

The United States is by far the world’s largest consumer and market for industrial diamonds. It is predicted that the U.S. will lead the world in diamond consumption well into the 21st century.