“You said HOW MANY carats?”

10 billion trillion trillion carats.

That’s how big the largest known diamond is. (Hint: We didn’t say the largest diamond in the world!)

As it happens, diamonds form in many parts of outer space where extreme conditions – such as the cataclysmic collapse of an imploding star – provide the heat and pressure required for their formation.

Casseopeia Neutron Star Supernova - Space.com
Image: Casseopeia Neutron Star Explosion – Space.com

Space diamonds are sometimes delivered to earth via meteorite impacts – but none of them can compare with the 5-million-trillion-trillion-pound crystallized carbon core of a white dwarf star in the Centaurus constellation. Nicknamed “Lucy” after the Beatles song Lucy in the Sky with Diamonds, it’s a cosmic show of extra-terrestrial bling that eclipses the biggest and brightest our planet has to offer.

As stars become too large to sustain their mass and begin to run out of fuel, they die in spectacular explosions called supernovae that produce the heavier, more complex elements of our universe. The gold you’re wearing right now began life in the heart of a neutron star, shattered and flung to earth in stellar explosions in early cosmic history. White dwarf stars like Lucy will eventually implode under their own weight, their remains crystallizing to form similar massive “space diamonds.” Scientists believe our sun (also a white dwarf) will end up the same way.

So, now you know.

BBC News: Diamond star thrills astronomers

Universe Today: Astronomers find a huge diamond in space