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Astronomers have spotted a planet that seems to be made of diamond. This new planet was found orbiting a tiny star J1719-1438 known as a Pulsar. Pulsars are dead neutron stars around 20 kilometers in diameter and spin hundreds of times a second, emitting beams of radiation. The Science journal reports that the planet, which orbits its star every two hours and 10 minutes, has slightly more mass than Jupiter but is 20 times as dense. Matthew Bailes of Swinburne University of Technology in Melbourne was quoted, “The evolutionary history and amazing density of the planet all suggest it is comprised of carbon -- i.e. a massive diamond orbiting a neutron star every two hours in an orbit so tight it would fit inside our own Sun.”
The planet never got large enough to produce elements heavier than carbon. So once the hydrogen and helium are stripped away, it would reveal a solid carbon core – made of diamond.