Natural
diamonds are pure carbon, formed into crystals deep below the earth’s
crust many millions of years ago. Diamonds are found and mined in
several parts of the world but predominantly in southern Africa where
flows of volcanic lava, known as Kimberlite, have carried diamond
deposits to the surface. These deposits can be mined or quarried to
recover the diamonds within the Kimberlite.
As
the hardest natural substance known to man, diamonds brought to the
surface in this way have survived the effects of geological erosion,
often being washed down river valleys and into the sea. Diamonds can
therefore be recovered from the alluvial deposits in rivers as well as
from the sea bed and even from beaches. In their recovered or “rough”
form they are far from the cut and polished gemstones which we prize
today.
Rough
diamonds have to be sorted and graded before those which can be used
for jewellery are shipped to specialist cutting and polishing centres
around the world. Diamonds not suitable for jewellery are used for
industrial cutting and drilling.