April’s birthstone is the diamond.
Diamonds are the rich cousins of graphite. Both are crystalline forms of pure carbon. The enormous differences in their properties are a result of the way the carbon atoms are bonded together. In graphite, carbon atoms are arranged in sheets that easily slide past each other, which makes graphite ideal as a lubricant and, of course, pencil lead. Diamond crystals, on the other hand, are a tight-fisted network of carbon atoms securely held in four directions, making it the hardest naturally-occurring substance in the world.
In order to achieve such a compact and strongly-held network of carbon atoms, it is believed that diamonds must have crystallized deep under the Earth’s surface. At these depths the proper conditions for the formation of diamonds exist; at 90 to 120 miles deep, pressures are more than 65,000 times that of the atmosphere at the Earth’s surface, with temperatures…
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