Here is something extraordinary!
I think a lot of people have already heard about this info, but I'll talk about it again: D
A planet made almost entirely of diamond was discovered at 40 light-years from Earth in the constellation of Cancer.
This famous planet is about twice the size of our Earth. The first time this planet was observed using a telescope was in 2011 when it passed its sun. Indeed, it is easier to see a planet as it passes in front of its star.
Moreover, she performs a complete turn around her sun in about 18h, against 365 days for our good old Earth :)
On the other hand, I think it will remain very difficult, if not impossible, to go harvest this ore in the decades or centuries to come. Already, this planet is really very far away, and above all it makes a temperature exceeding the 2000 ° on its surface!
While waiting for a real colonization of space by Man, it leaves us dreamer. And I hope with all my heart that we will find in the future such beautiful natural treasures and more!