A diamonds journey begins 120 to 200km’s below the earth’s surface in the earth’s upper
mantle. It takes extreme temperatures and pressures for diamond crystals to form.
The average age of a diamond is estimated at 3.3 billion years old.
Diamond crystals are mainly found in two types of geological locations – Kimberlite (Blue
ground) or Alluvial deposits.
Diamond mines where diamonds are recovered from kimberlite are known as primary diamond
deposits. In primary deposits, diamonds crystals are transported in magma which solidifies into
the igneous host rock, kimberlite on its way to the earth’s surface.
In the magma, the perfect form of the diamond is attacked and rounded on its way to the earth’s
surface. A perfect uncut natural diamond crystal can be very expensive and is called a “glassy”.
Diamonds that are recovered from alluvial deposits are known as secondary diamond deposits
as these diamonds have been transported by wind or water to an area where they are found in
nearby rivers and streams.
To understand the rarity of diamonds, it takes over 250 tons of kimberlite ore from a primary
deposit to produce 1carat weight of diamond. Of this 1 carat, only 25 percent may be of
gemstone quality. The non-gemstone quality diamonds can be used for industry and tooling.
The world’s major diamond sources include: Australia, South Africa, Russia, Botswana, USA
Diamond Education Videos (You Tube):
Click on this GIA link to understand diamond grading.