The results of space exploration over the last 2 years have provoked considerable and widespread interest, among geoscientists, in the interiors of the outer planets. Even new data on remote Uranus and Neptune are becoming available, and so it is not unusual to expect a round of new speculation on their interior compositions and properties. In a very recent article in Nature (292, 435–436, 1981), one of the most eminent theoretical physicists in the field of gas thermodynamics at high pressure has developed a model of the layered structures of Uranus and Neptune. Marvin Ross of the University of California (Lawrence Livermore National Laboratory), taking into account the knowledge that the outer planets have an inner layer, or mantle, consisting of forms of water, methane, and ammonia (in addition to various proportions of hydrogen plus helium in solar abundance), suggests that there could be a process that forms diamonds and metallic compounds. In the Nature article, entitled ‘The Ice Layer in Uranus and Neptune—Diamonds in the Sky?,’ Ross makes a serious analysis of existing shock wave and theoretical data on methane, carbon, and hydrogen with which he compared the interior of Uranus (Neptune is very similar, he says). The results could have far reaching implications in the theory and understanding of the solar system. The postulation properties of the mantles of Uranus and Neptune could cause magnetic fields and the generation of radio waves.