It's called BPM37093 and it's located in Centaurus constellation

The scientist nicknamed it as "Lucy", as the Beatles song "Lucy in the Sky of Diamonds", but it has nothing to do with the English band or the primitive woman found in Ethiopia.

Lucy, or BPM 37093, is simply a star, which has arrived till the end of its evolution, becoming a white dwarf star, or to be more precise, a blinking white dwarf star (it means that its brightness is variable during a reasonable period of time)

Why is it a... diamond?

So, as written in a previous post of mine, a star burn hydrogen to transform it in helium. When the hydrogen finishes, a new thermonuclear reaction start, this time burning helium, transforming it in heaviest elements and the first which is formed is carbon

HYDROGEN ----- HELIUM ----- CARBON ----- ..... 

We also know that, in these phase, gravity and thermonuclear reaction pressure try to balance themselves, but at this time the star condition is UNSTABLE. If the star has not sufficient mass to continue the thermonuclear reaction after carbon, slowly loses a part of the carbon matter and start to get smaller and smaller. This happens because the core reaction gradually ends, the balance breaks down and the gravity gets stronger and stronger, shrinking the star size.

All that carbon under a very strong pressure (due to the gravity, obviously) is simply a diamond! The biggest diamond ever discovered. Its weight is approximately 10^34 ct (about 2 x 10^24 tons)

Unfortunately no-one of us could steal it (steal a star? Haha :D). It's too far: 50 light-years far from the Earth.