An
age-old status symbol of luxur y and
wealth, the cr ystal of carbon better known as
diamond is a must-have jewel to adorn a ring finger.
Its entrancing sparkle (measured as brilliance or
lustre), characteristic properties such as its hardness,
and longstanding role in western marriages have
ensured that a diamond does not come cheaply.
Yet, its high value is not derived from its rarity –
rather, diamonds are counter-intuitively the most
common gem, surpassing the more affordable
rubies, sapphires and emeralds in abundance.
D i amonds we re b rought to unpa ra l l e l ed
demand in the 1930s when De Beers Diamond
Company (holdi ng 90% of the wor ld’s enti re
diamond suppl y) launched the wor ld’s mos t
successful advertising campaign, convincing the
public that “diamonds are forever”. Simultaneously,
De Bee r s pe r manen t l y s l a s hed wo r l dw i de
production, artificially raising the price of diamonds.
In an effort to combat the stranglehold of De Beers
and other cartels on the diamond supply, scientists
have been attempting to perfect the synthesis of
lab-made diamonds from raw carbon. The quality
of these synthetic diamonds is rapidly reaching that
of natural diamonds, turning a scientific endeavour
into a high-stakes gambit.
Diamonds have been mined in India since at
least 3000 years ago, but it was not until the 18
th
century that they were shown to be composed
of carbon. Lavoisier used a lens to concentrate
sunlight onto the surface of a diamond in a vessel
f i l led with oxygen. The diamond combus ted
spectacularly and the vessel’s air was precipitated
in limewater, producing a milky solution. Through
this experiment, Lavoisier was able to show that
diamond reacts with oxygen to produce carbon
dioxide. Lavoisier deduced that since diamonds
and charcoal both produced CO
2
, they must be
made of the same substance: carbon [1]. Tennant
later proved that since the combustion of diamond
and graphite both produce the same volume of
CO
2
, they must be equivalent forms of carbon.
Natu ra l d i amond fo rmat i on requ i res the
conditions of high pressure (4.5 – 6 GPa) and
high temperature (900 – 1300 °C). Within the
Earth’s mantle, there is sufficient pressure
exer ted by the weight of the rock
above and sufficient thermal energy
provided by the Ear th’s core. These
areas of the Earth are hardly accessible, but
deep and violent volcanic eruptions around
47 million years ago brought these diamonds
to t he s u r face. D i amond s fo rm i n t he
mantle within the volcanoes’ ejecta. Rapid
cooling of the ejecta lock the carbon atoms
in place (otherwise, graphite would form).
Most naturally formed diamonds are mined
from rocks called Kimberlites. Diamonds are also
sometimes formed from the impact of diamond-
laden meteorites. The collision generates sufficient
pressure and temperature for diamond formation
to occur.
Upper
Mantle
Diam
Synthetic
