Diamond is hard, but is also brittle, so might not be ideal. A good material for the back would actually be jade, being amongst the 'toughest' minerals known. It is also fairly hard and would not be easily scratched. Might be a bit expensive for margin obsessed Apple. A good synthetic material would be PSZ, an extremely 'tough' ceramic developed by the CSIRO in Australia.
11/10/10 at 2:37am