
Diamond is the hardest natural material known having extreme resistance to scratching. But it is not tough at all so don't try your hammer on it. If you insist on destroy your diamond then the most spectacular - and nevertheless a very expensive - method is to heat it to more than 800 degree Celsius where it converts to graphite quickly enough to observe.
The largest diamond found on Earth was the Cullinan, in 1905, which weighed 3,106 carats. But this is not the largest one we know about. In 2008, scientists discovered that a star, namely the BPM 37093, which is located 50 light years away from Earth has a diamond core 2,500 mile wide weighting approximately ten billion trillion trillion carats.