Nanoscale gemstones source of mysterious cosmic microwave light

Some of the tiniest diamonds in the universe – bits of crystalline carbon hundreds of thousands of times smaller than a grain of sand – have been detected swirling around three infant star systems in the Milky Way. These microscopic gemstones are neither rare nor precious; they are, however, exciting for astronomers who identified them as the source of a mysterious cosmic microwave “glow” emanating from several protoplanetary disks in our galaxy.