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九月 2016

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How Diamonds are Formed: In Nature & In the Lab

Everybody knows how diamonds are formed from coal, right? That old myth about how diamonds are formed is giving way to a more accurate description of the birth of a natural diamond. Diamonds are actually created through the connection and bond made by highly organized carbon materials. What exactly the carbon materials are, and how they came to be found in the area where diamond creation occurs, is still somewhat of a mystery. But it is thought that the carbon is residue from plants, animals and shells that eventually broke down and were absorbed into the earth’s mantle, making its way nearly one hundred miles below the surface, to begin a process that would create one of the most beautiful and sought after materials on the planet.

How Diamonds are Formed: Nature’s Way

The carbon material on its own cannot form a diamond. The conditions surrounding how diamonds are formed are precise and intense. A diamond needs both very high temperature and very strong pressure in order to metamorphose from its basic carbon form into the gem we see in jewelry all over the world. Under the duress of approximately 725,000 pounds per square inch, and at temperatures of 2000 – 2200 degrees Fahrenheit, a diamond will begin to form. The carbon atoms bond together to form crystals under this high pressure and temperature. Each carbon atom bonds with four other carbon atoms, creating the diamond’s renowned strength – as the world’s hardest substance.

So how does a diamond get from the depths of the earth’s mantle to the surface? The majority of diamonds found today in commercial mines and deposits were brought to the surface through violent volcanic eruptions. This process is believed to have happened extremely quickly, likely in a matter of hours, with the diamond formations traveling at rates of 20 – 30 miles per hour. Had the process not happened this quickly, the result would have turned the diamond into graphite along the way. The diamonds brought to the surface are then contained within pipes, known as Kimberlite. Kimberlite is cooled volcanic material, which keeps the diamond locked in its natural form. Scientists are still struggling to figure out how long it takes diamonds to form. It is impossible to replicate the exact scientific conditions within a lab – temperature and pressure notwithstanding. So, the best science can do is carbon date the minerals surrounding the diamond formation in order to determine the age, typically between hundreds of millions of years and 1 to 3 billion years.

Synthetic Diamonds: The Man Made Alternative

Synthetic diamonds are grown with the use of technology that replicates the conditions under which a natural diamond develops. There are two methods for creating man made diamonds, but they are not equal.

The first method is called HPTP, or high pressure, high temperature. This method uses a piece of graphite, similar to that found in a generic number 2 pencil. The graphite is placed in a machine where it is treated with intense heat and pressure, mimicking natural conditions. This method can form a diamond within a few days, however, because the process requires adding a metal solution to the graphite, the end result is not as pure as a natural diamond. Therefore these diamonds are generally used for industrial purposes.

The second method of lab growing diamonds is chemical vapor deposition. This method can create diamonds that are more flawless than those found in nature. How does it work? A “seed” diamond, usually a fingernail-sized sliver of a natural diamond, is placed in a vacuum chamber, where it is then zapped with microwave rays, while methane and hydrogen gas are introduced into the process. The gas is then heated to a temperature of nearly 2,000 degrees, while the vacuum chamber applies pressure. The result causes the gas atoms to stick to the diamond, creating a perfect sheet of diamond overnight.

Earth or Lab? The End Result

Fancy colored diamonds are created in a lab the same way they are created in nature: through the introduction of small amounts of specific trace elements, such as boron, which creates deep blue, nitrogen, which creates yellow, or hydrogen, which creates purple. Whether in a lab or in nature, the mixture of these elements during the diamond’s formation provides the same result.

Lab grown and natural diamonds are so similar that even the most expert jewelers have trouble telling them apart with the naked eye. Industry professionals are working to create better tools for differentiating between synthetic and mined diamonds, such as De Beers’ recent launch of new synthetic diamond detection technology. History, romance, folklore and tradition aside, the reason synthetic and natural diamonds appear so similar is because – structurally – they are.

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