Artificial Diamonds - Now Available in Extra Large
Improved Quality of Synthetic Diamonds Threatens the Natural Diamond Market
Diamonds are a girl's best friend, they say - and soon they could be every girl's best friend.
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A team in the US has brought the world one step closer to cheap, mass-produced, perfect diamonds. The improvement also means there is no theoretical limit on the size of diamonds that can be grown in the lab.
A team led by Russell Hemley, of the Carnegie Institute of Washington, makes diamonds by chemical vapour deposition (CVD), where carbon atoms in a gas are deposited on a surface to produce diamond crystals.
The CVD process produces rapid diamond growth, but impurities from the gas are absorbed and the diamonds take on a brownish tint.
These defects can be purged by a costly high-pressure, high-temperature treatment called annealing. However, only relatively small diamonds can be produced this way: the largest so far being a 34-carat yellow diamond about 1 centimetre wide.
Microwaved gems
Now Hemley and his team have got around the size limit by using microwaves to "cook" their diamonds in a hydrogen plasma at 2200 °C but at low pressure. Diamond size is now limited only by the size of the microwave chamber used.
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