Ha I knew about the diamond planet from this pic I saw a while ago :D
To the dissapointment of some, we are not 100 % sure it's made of diamond.. Copy-theft from wiki: "much of which may be in the form of diamond as a result of the temperatures and pressures in the planet's interior. Further observations are necessary to confirm the nature of the planet"
Yep right, although there's actually more than one; a second was discovered with the even catchier name 'PSR J1719-1438 b'. I didn't want to use this one though because there are some other... awesome things about it that I don't want to discuss just yet.
But it's supposedly a whole new class of 'carbon planets' that we may have stumbled across.