Glittering stars in the night sky aside, scientists have long known that some diamonds hail from the heavens. In 1981, for example, when Smithsonian researchers tried to cut through a large iron meteorite that had crash-landed in the Allen Hills of Antarctica, the sawteeth on their blade got all chewed up. Subsequent X-rays showed that the stone was riddled with microscopic diamonds, the hardest substance known. The scientists theorized that the meteorite's diamonds were born during a cataclysmic collision out in the asteroid belt. Find out more in this article from NOVA Online.