The biggest ever diamond has been found floating in space. The gem, estimated at close to 10 billion trillion trillion carats, is at the core of a dead star (BPM 37093) - a crystallised white dwarf.

The newly-discovered diamond in the sky is a whopping great chunk of crystallised carbon 50 light-years from the Earth in the constellation Centaurus. It is 2,500 miles across (the moon is approximately 2,200 miles across) and weighs 5 million trillion trillion pounds. It has been dubbed "Lucy" in reference to the Beatles' song, "Lucy in the Sky with Diamonds". Diamond specialists told the research team that if nothing else, the diamond was much too big to wear*.

Theorists have long speculated that the cores of extinct white dwarves would crystallise, but until now have had no way to prove it. However, the white dwarf is not only radiant but also harmonious. It rings like a gigantic gong, undergoing constant pulsations.

"By measuring those pulsations, we were able to study the hidden interior of the white dwarf, just like seismograph measurements of earthquakes allow geologists to study the interior of the Earth. We figured out that the carbon interior of this white dwarf has solidified to form the galaxy's largest diamond," explained Travis Metcalfe, head of the team at Harvard Smithsonian Centre for Astrophysics.

Our own Sun will become a white dwarf when it dies 5 billion years from now, having first expanded to engulf almost everything in the solar system. Two billion years after that, the core will crystallise, leaving a giant diamond in its place. ®

*Ms. Lopez, please take note: there are limits...