astronomyblog:

The atmosphere of Neptune is, in many ways, similar to that of Uranus. However, its dynamics are presented in a complex configuration of strong winds that sweep the planet, besides the formation of cyclonic storms and clouds, with clearly visible visual characteristics. 

The upper atmosphere of Neptune is made up of 79% hydrogen, about 18% helium and most of the remaining methane, the presence of which imparts the blue-indigo color of the planet by absorbing the incident red radiation.

The diamond rain on Neptune and Uranus was predicted long ago, because of the pressure inside the planet that could be formed by carbon and hydrogen. But now it was virtually confirmed by an experiment conducted by an international team of scientists, this “diamond rain” was recreated under laboratory conditions for the first time, giving us the first glimpse into what things could be like inside ice giants.

At about 10,000 km below the surface of these planets, hydrocarbon compression is thought to create diamonds. To recreate these conditions, the international team submitted a polystyrene plastic sample to two shock waves using an intense optical laser in the Matter in Extreme Conditions (MEC) instrument, which were then paired with X-ray pulses from Linac Coherent Light Source SLAC (LCLS).

Polystyrene is made from a mixture of hydrogen and carbon, key components of the general chemical composition of the ice giants. In the experiment, the team was able to see that almost all of the carbon atoms in polystyrene were embedded in small diamond structures up to a few nanometers wide.

However, in Uranus and Neptune, scientists predict that diamonds would become much larger, perhaps millions of carats by weight.

2°image: (This false color photograph of Neptune was made from Voyager 2 images taken through three filters: blue, green, and a filter that passes light at a wavelength that is absorbed by methane gas. Thus, regions that appear white or bright red are those that reflect sunlight before it passes through a large quantity of methane). 1°image, 3°image & 4°image.

Here are two links if you want to read about it: Click here and here.