Method — High Pressure High Temperature (HPHT)
The method itself was developed in the middle of 1950s and
has since been modified by various research laboratories specializing
in diamond synthesis around the world. The highest quality
lab-made diamonds are grown using variants of this method;
the most successful involves growing the diamonds in a 'flux'
of molten metal alloy.
HPHT method recreates the actual geological conditions that
occur 150 km deep in the Earth's mantle. The conditions are
a unique and powerful combination of extreme pressure (up
to 60,000 atmospheres) and very high temperature (up to 2,500°C),
which are the natural conditions for diamond formation.
The equipment itself is known as 'split sphere' technology
or 'BARS'. The machinery utilizes a built-in growth cell where
the carbon seed of a crystal is placed and where extreme pressures
and temperatures are applied. The atoms of carbon are transformed
and grow into what is known as the hardest and most perfect
substance found in Nature - the Diamond.