How are diamonds made?
Diamonds form naturally deep beneath the Earth's surface, but they can also be made in a laboratory
by diamond manufacturers. Read on to learn about the variety of ways in which we can find and produce
this highly sought-after gemstone.
Natural diamonds are formed from pure carbon at a depth of around 100 miles below the Earth's surface.
The process of diamond formation occurs over millions (or even billions) of years within the molten rock of the
Earth's mantle, where the right amounts of pressure and heat can be found to transform carbon into diamond. The
diamonds are then carried through flows of molten lava to the Earth's surface where it is mined and turned into
the precious stones we used to make jewellery.
There are two ways of making synthetic diamonds in a laboratory, both of which are used by diamond
manufacturers. The first synthetic method is known as 'high pressure, high temperature', or HPHT for
short. This method is the closest thing to the diamond production process that occurs naturally within
the Earth, and involves subjecting graphite (which is made from pure carbon) to intense heat and
Tiny pieces of metal in the HPHT machine are used to squeeze down the graphite as it is zapped with
an intense pulse of electricity. This process takes just a few days and results in a gem-quality
diamond. Unfortunately, this type of synthetic diamond is not as pure as a natural diamond, because
part of the metallic solution used to form the diamond can become mixed in with the graphite.
The second diamond-producing method is called chemical vapour deposition. This method produces
diamonds even more flawless than those found in nature. Chemical vapour deposition involves placing a
piece of diamond into a depressurising chamber, where it is treated with a natural gas under a microwave
beam. When the gas heats to around 2,000 degrees, carbon items rain down onto the diamond and stick to it.
Using this process, manufacturers can grow a perfect sheet of diamond overnight.