Astronomy Photographer of the Year competition. Quick, make a wish! A meteor streaks across the sky above Arches National Park in Utah during the annual Perseid meteor shower, one of the most prolific meteor showers in the universe.
Diamond is the ultimate gemstone, having few weaknesses and many strengths. It is well known that Diamond is the hardest substance found in nature, but few people realize that Diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). But even as hard as it is, it is not impervious. Diamond has four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it can cleave, or split.