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Scientists are “growing” diamonds in a Welsh laboratory – and claim their gems are purer than the real thing.

Researchers at Cardiff University take just days to make precious stones which would take millions of years to mature naturally.

The physicists combine methane and hydrogen gases to produce the lab-grown diamonds, and say they are better than those produced by Mother Nature.

Professor Oliver Williams said: “The diamonds are purer than anything you would see in nature.

“With the best growers, less than one atom in a trillion is an impurity.”

(Image: Dominic Lipinski/PA)

Prof Williams, of the university’s school of physics and astronomy, leads a team making diamond sheets for research into semi-conductors – but the same process can be used to grow gems.

The team start the process by putting a small “seed” diamond in a vacuum chamber to exclude air, then pump in methane and hydrogen gas heated to 3,000C which forms a plasma.

The gases break apart, with carbon from the methane being deposited on the seed diamond, and the carbon copies the crystal structure of the diamond.

Prof Williams said: “It’s man actually beating nature.

“We’re perfecting it and it’s an enormous accomplishment to grow a material that traditionally has been very difficult to grow.”

(Image: Western Mail)

Several companies around the world are now growing diamonds for jewellery, with prices around 15-20% less than a natural stone of the same size.

But although man-made diamonds are now being sold at some high-end jewellers, industry bosses say customers currently still prefer the real deal.

Sentimental quality

Jean-Marc Lieberherr, chief executive of the Diamond Producers Association, said the value of a gem is partly due to its sentimental quality.

“The fact they cannot be distinguished with the naked eye does not make them identical, or equal.

“Think of very good replica of a Picasso painting.

“We might not be able to tell it apart, but with the right equipment an expert will be able to.

“One has enormous monetary and emotional value, one is a replica with no inherent or resale value.

“It’s the same thing with diamonds – effective industrial replicas of the real thing.”