Neptune is referred to as an 'Ice Giant' because its outer layers are made of helium and hydrogen. The methane in the atmosphere creates its exterior bluish hue. The 'ice,' in astronomy terms, refers to the compounds of elements that contain hydrogen. The water, ammonia, and methane make it icy (via American Scientist).
Neptune's hydro-helium atmosphere has paved the way for the belief that its gravity compresses interior ice at a high density, and heat raises temperatures, mixed with extreme pressure, to form a hot and icy precipitation of diamond formations.
An experiment, courtesy of the Linac Coherent Light Source (LCLS) X-Ray Laser, housed at the SLAC National Accelerator Laboratory, offered the most exact measurements to date on the possible diamond-making process that occurs on Neptune (via Science Alert).
The experiment report proclaimed "carbon transitions directly into crystalline diamonds." Mike Dunne, the director of the LCLS stated, "This research provides data on a phenomenon that is very difficult to model computationally; the 'miscibility' of two elements, or how they combine when mixed. Here (in this case) they see how two elements separate, like getting mayonnaise to separate back into oil and vinegar."
The experiment is important in revealing just how strange the planet actually is because of the hot center of the icy planet. Due to the gravitational energy emitted, it could confirm the previous hypothesis that the heat and friction, along with the materials around them, are forming diamonds.
