Planets where it rains diamonds

On Jupiter and Saturn, the atmosphere is so extreme that it turns soot into solid diamonds. It starts as methane gas in the upper atmosphere, which gets hit by lightning and turned into clouds of black soot.

As this soot falls toward the core, the atmospheric pressure increases to over 100,000 times that of Earth. This massive weight crushes the carbon into graphite and then eventually into hard, solid diamonds.

In the deepest layers of these planets, these diamond hailstones are estimated to be about a centimeter in diameter. Some researchers estimate that atmospheric conditions could potentially produce up to 1,000 tons of diamond material on Saturn annually.

However, you can't go there to collect them. Once the diamonds fall deep enough, the heat becomes so intense that they actually melt. At the very core, it is likely that there are literal oceans of liquid carbon, create a permanent cycle of solid gems turning back into a metallic soup.

On Neptune and Uranus, the pressure is even higher, which might lead to the formation of "diamond icebergs" floating on seas of liquid diamond.