Image kindly reproduced according to the licence at: http://en.wikipedia.org/wiki/File:Diamond.jpg
The hardest ever produced.
Made literaly from air!
The technique is called ‘chemical vapour deposition’ and the gems are good enough to be used in jewellry.
How? (I hear you ask!)
That’s the tricky part.
A ‘rain’ of gaseous carbon is deposited onto the surface of an existing diamond, forming a thin film of diamond.
The rain is a plasma, generated by bomarding methane and hydrogen with charged particles.
The thin film of diamond is then cut up and exposed to exceptionally high pressures (50,000 – 70,000 times normal atmospheric pressure – that is not a typo!) and high temperatures (2000 oC).
And hey presto, exceptionally hard diamonds are produced! Easy, eh? 🙂
Blog posting adapted from an article in New Scientist magazine, 6th March 2004, page 17, ‘What a diamond a day makes’.