Diamond Planet. Credit: Swinburne Astronomy Productions. A Jupiter-mass planet orbiting the newly discovered pulsar PSR J1719-1438 is likely one gigantic diamond. The planet's ultra-high pressure has caused the carbon within it to crystallize into diamond. And the weirdness doesn't stop there. The planet was probably once a star, but most of its mass was sucked off by its tiny pulsar companion, which is spinning at a rate of 10,000 revolutions per minute. It is 4,000 light-years from Earth.