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Roger Weller, geology instructor

Melanie Lewis

Physical Geology
Spring 2005

Learning about Diamonds

            Every woman in the world is in love with diamonds, as am I.  From early childhood on, when I saw my mother putting on her diamond jewelry, I knew that, when I grew up, I would have my own collection of diamonds to show off.  Today, I am beginning to start my collection.  At only nineteen, I have a dozen pieces of diamond jewelry to wear and enjoy.  Loving diamonds so much, I decided to learn more about them in order to appreciate them even more.

            I have always known that diamonds are found in the earth by mining, but I never knew all the details.  It turns out that diamonds are transported to the earth’s surface by molten rock, or magma, that originates at great depths within the earth.  This magma, which is carrying diamonds and other materials and forms the earth’s mantle, rises and erupts into volcanoes.  Underneath those volcanoes is a carrot shaped “pipe” filled with volcanic rock, mantle fragments, and embedded diamonds.  The rock in which the diamond is embedded is called kimberlitic, after the city of Kimberley, South Africa where the pipes were first discovered.  Another type of rock that provides diamonds is lamproite.  It has been determined by the search for diamonds, that most are derived from kimberlitic pipes in the oldest nuclear areas of the continent, where the rocks are older than 1.5 billion years (American).

            It is interesting to find out what exactly the diamonds that I am wearing are made out of.  During my research I learned that diamond is carbon in its most concentrated form, and except for trace impurities like boron and nitrogen, diamond is composed entirely of carbon, which is the chemical that is fundamental to all life.

            Many people have the misconception that diamonds only come as colorless stones.  In reality, diamonds come in many different colors.  A diamond can be almost any color in the rainbow.  Colored diamonds are often referred to as “fancies” (Nature).  The colorless diamond is a chemically-pure crystal, but by adding nitrogen, a yellow diamond can appear, and by adding boron, a blue diamond can appear.  Many other colors such as red, violet, real white, and black are possible colors for diamonds (American).  Today, people are moving away from the classic clear diamond and moving towards more color, although the colorless diamond will always stay very popular.

            Diamonds  are known for their hardness, which is the measure of a substance’s resistance to being scratched.  The diamond is the hardest substance known to man, and only a diamond can scratch another diamond (American).  Because diamonds can withstand such extremely high temperatures and corrosive conditions, they are ideal for use as windows in industry and in space probes.  Diamond is also used for scalpels, and it is very effective because of its sharp, hard edges that never dull, and also because diamond’s hydrophobic surface ensures that wet tissue does not adhere to the blade (Nature).  On Mohs scale of hardness, diamond is ranked the hardest material, because it can scratch other materials with a lower ranking.

            Diamond is not fragile or even prone to breaking, but all substances can fracture or shatter.  Because of its particular crystal structure, diamond has certain planes of weakness along which it can be split.  It is said that diamond has perfect cleavage in four different directions, meaning that it will separate neatly along those lines instead of becoming jagged or irregular.  Diamond is also very dense given the low atomic weight of carbon (American).

            One of the things that draws women to diamonds, is that unbelievable shine and luster that they give off.  Every woman enjoys the feeling of being the center of attention when she walks into the room with a gleaming stone on her finger.  Diamond has a great ability to refract light, which means to bend or slow down light, as it passes through it.  Diamond also displays the maximum amount of reflectance for a transparent substance, displaying what is called an “adamantine” luster.  Diamond also has an unusual property for a mineral, which is that it can repel water.  Diamond’s strong bonding and carbon composition cause its surface to repel water, but readily accept wax and grease.  Those two properties provide an effective means of separating diamonds from other minerals that come out of mining operations.  Washed gravel containing diamonds is flushed with water over a sloping surface covered with a mixture of wax and grease.  The diamonds stick to the table, while the wetted waste minerals wash away over it.  Diamonds readily pick up a greasy film, as can be seen on one’s jewelry, but cleaning them with ammonia or a good detergent restores their brilliance (American).

            I never knew exactly how many places in the world mined diamonds until I learned that today diamonds are mined in about 25 countries, on every continent except Europe and Antarctica, including major producers from several South African countries, Siberian Russia, and Australia.  Only a few diamond deposits were known until the 20th century.  For 1000 years starting in the 4th century, India was the only source of diamonds.  In 1725, important sources were discovered in Brazil, and in the 1870’s major finds in South Africa marked a huge increase in the diamond supply (American).  The largest rough diamond ever found was the Cullinan, 3,106 carats, discovered in 1905 in the Premier mine of South Africa (Nature).

            Today diamond symbolizes wealth, durability, status, and peerless quality.  Across time and cultures diamond has also been associated with invulnerability, lightning, magic, healing, protection, and poisoning (American).  To me diamonds symbolize timeless grace and beauty that will never fade away.  Diamonds have shown up as many forms of jewelry from earrings to necklaces.  But the most prominent piece of diamond jewelry is the ring.  May it be engagement rings, a wedding ring, or an anniversary ring, one or more diamonds are always present.  But in ancient times diamonds were not used as jewelry, and instead they were used for such purposes as engraving other gems like sapphire, and for drilling holes into headstone beads (Nature).  Today we are taking diamond use back towards the ancient times with eighty percent of the diamonds mined annually being used in industry.  Diamond has three primary roles in industry:  it can be used as a cutting tool, it can be imbedded in another material and used as a tool or an abrasive, and it can be turned into powder or paste for grinding and polishing (American).  An interesting discovery for me was when I learned that every copper wire in my computer, television, and house had been shaped with a die, the device that squeezes wire to the desired diameter, made from diamond (Nature).  Diamond is selected in the industry for such use where its hardness and resistance to abrasion, its long working life, and fast cutting action outweigh its cost (American).

            To me diamonds will always be the most beautiful and valuable things that I own.  It has been fascinating to learn more about my favorite gemstone.  I never knew about many of the things like mining and industrial use until I researched.  It is really fun to know that diamond is so much more than just a stone that sits in a ring and looks nice, but actually does a variety of useful things.   


Works Cited

American Museum of Natural History.
The Nature of Diamonds:  Facts About Diamonds.  San Diego Natural History Museum.