April's birthstone is the diamond. Even from a geological perspective, diamonds are pretty neat.  Their cold sparkling fire has held us spell-bound for centuries, inspiring rich  myths of romance, power, greed, and magic.

     There are many kinds of diamonds. Some are transparent, others translucent or opaque; ranging from colorless to sooty black, with many colors in between. Transparent or slightly tinted diamonds are most often used in jewelry. The others are more widely used in industry. The color of a diamond depends on the kind of impurities embedded inside it. Yellow diamonds have minute traces of nitrogen. Boron imparts a bluish hue.

      Given how valuable diamonds are, it is with some irony that graphite is their cousin! Both are crystalline forms of carbon. What makes diamond differ from graphite is how the carbon atoms are bonded together. Graphite's carbon atoms are arranged in sheet form, while diamond's carbon atoms are a compact network of securely bonded on all sides. The end result is that graphite makes great pencil leads or lubricants while diamonds are the hardest natural substance in the world.
Geologists believe that diamonds form deep within the Earth At a depth of about 100 miles, atmospheric pressure exceeds 65,000 times that of the atmosphere at surface level. Temperatures exceed 2700 degrees F. We use conditions like this to create synthetic diamonds.

 
    Diamonds are found in alluvial deposits -- gravel swept by streams, rivers, glaciers and  ocean currents.  It is thought that the oldest diamonds come from samples of kimberlite, a volcanic rock found in South Africa. Tiny flecks of diamond have been found inside meteorites.

     In their natural form, diamonds are quite unimpressive. It is nly when they are cut and polished so that the light entering it is reflected and refracted as best possible is their beauty revealed.  How does one cut such a hard stone? Diamonds must be cut along planes parallel to the faces of the crystal where the tight bonds between carbon atoms are a little weaker.

     Diamonds were once rare and because of their beauty, have a rich legacy. One of the oldest and most valuable diamonds is the Koh-i-noor diamond. It is believed to be over 6000 years old. Originally owned by the Rajah of Malwa in India, the Koh-i-noor has since  been a player in victories and defeats spanning India, Persia and Afghanistan. It was in the possession of the great Mogul dynasty from 1526 to 1739, when the Taj Mahal was built. The Persian invader Nadir Shah briefly possessed it until his assassination in 1747. Eventually it came back into India under British rule.  The stone was presented to Queen Victoria who had it cut from its original 187 carats to 108 carats in an attempt to further enhance its beauty. After her death, the diamond became part of the British Regalia, and was worn by Queen Elizabeth, the Queen Mother in her 1937  coronation. Today, the Koh-i-noor diamond is worn as a brooch by the Queen Mother on  ceremonial occasions.

     Ancient Hindus, finding diamonds washed out of the ground after thunderstorms, believed they were created by bolts of lightning. In our place and time, the diamond is a symbol of enduring love. The one myth which is widely held today about diamonds is that they are rare. Diamonds are by no means rare. In fact, so many diamonds have come out of the mines of South Africa that the company which owned the mines had to put most of them in storage. Now, they release just so many per year. To release all of the diamonds they own would flood the market and drive the price down to a bare fraction of what it is! Diamonds may be some girl's best friend, but their sheer numbers are a best kept secret!