Planets made of Diamond
Most of us are intrigued and often mesmerised by Earth’s most precious (and hardest) gemstone: the diamond. Most natural diamonds are formed at high temperature and pressure at depths of 187 to 118 miles in the Earth’s mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Imagine an entire planet made of diamond - it has been discovered that such celestial beings actually exist!
Also known as ‘carbon planets’, there are a handful of these carbon-rich planets (including ‘55 Cancri e’ and a few in the pulsar ‘PSR 1257+12′) being researched that, as a result of the high pressures and temperatures of the planets’ interiors, comprise largely of actual diamond. Carbon planets might also be located near the galactic core or globular clusters orbiting the galaxy, where stars have a higher carbon-to-oxygen ratio than the sun. When old stars die, they spew out large quantities of carbon. As time passes and more and more generations of stars end, the concentration of carbon, and carbon planets, will increase. Quiet something to stir up the imagination!
(info sourced from www.wikipedia.com)