Billion-trillion-trillion-carat diamond discovered

Space scientists say they have found the biggest known diamond in the universe - a 10-billion-trillion-trillion-carat gem.

United States astrophysicists say the massive rock is 50 lightyears away in the constellation Centaurus. The cosmic diamond is a chunk of crystallised carbon in the core of a white dwarf star. It is 4000km across and weighs 2.27 million trillion trillion kg, which translates to about 10 billion trillion trillion carats, or a one followed by 34 zeros.

"It's the mother of all diamonds," says researcher Travis Metcalfe of the Harvard-Smithsonian Centre for Astrophysics.