Natural diamonds are formed in the intense pressure and heat of the Earth's mantle at depths of over 100km.

Jem Stansfield attempts to grow diamond crystals, using the heat of an oxy-acetylene welding torch.

A new series of Bang Goes the Theory starts on Monday, 15 August 2011 at 19:30 BST on BBC One. Watch more clips or catch-up via iPlayer at the above link.

Please note: The experiment is extremely difficult to perform, requires expert guidance and the tiny diamonds produced are too small to be of commercial value.