Diamonds: How Do They Form?
By Bryan Boyne (g.g.) , Thursday, May 05, 2016
Diamond is composed of pure carbon. But carbon typically takes mineral forms that are much less exciting than diamond! Graphite that is used in pencil lead is a common form of pure carbon. Coal is another common form of carbon that, while useful, shares none of the gem qualities of diamond. Differences in the way the carbon atoms are organized account for the differences in form. In order for carbon to crystalize in the form of diamond, tremendous temperatures and pressures are required. In our natural world these conditions only exist at great depths beneath the crust of the Earth. Most diamonds found on earth today formed billions of years ago.
Natural Diamond Formation Zone
How a Diamond is Formed
In order for diamond to form there must be an available source of carbon and relatively narrow ranges of temperates and pressures must align. This happens around 100 miles below the crust. Once crystalized the diamonds must be rapidly transported to the surface without undergoing substantial change. This requires an “elevator” ride inside a volcanic pipe. The most common type of volcanic pipe in which diamonds are found is a kimberlite pipe. Lamproite is another type of pipe that can contain diamond.
Because of the very special conditions required for the formation of diamond, and the rare volcanic events that bring them to the surface, gem diamonds that come within the reach of man are very rare. Diamonds have been found in a select number of kimberlites scattered around the planet. But not all kimberlite pipes contain diamond. Some that do contain traces of diamond, do not bear enough gem material to be economically viable to mine.
Diamond and Non-Diamond Kimberlite Pipes
Where are Diamonds Mined?
As mentioned, diamonds are found in some kimberlite and lamproite pipes. When a source pipe is discovered that contains sufficient diamond, it is mined in a “big dig” corporate operation involving heavy machinery and sophisticated technology to uncover and process diamond bearing rock.
In other locations diamonds are found among other rocks and minerals in alluvial deposits. These are gravels that have been eroded over the millennia from the host rock. They are often found in association with rivers which in many cases have transported the diamonds great distances from the original source. Because these deposits can often be “mined” by simple methods they are likely sites of artisanal digging by individual workers.
Diamonds were originally mined in India from alluvial deposits. In the late 1800’s diamonds were discovered in South Africa in volcanic pipes near the town of Kimberley, from which Kimberlite gets its name. These discoveries gave rise to large scale mining and resulted in the establishment of DeBeers Consolidated Mines, which dominated the market for the better part of the twentieth century. At one point it was estimated that DeBeers controlled 80% of diamond production worldwide.
Today, significant production comes from Russia, Australia and Canada as well as Africa and South America. Diamonds have been found all over the world, but in most cases, not in commercially viable quantities. In the United States many diamonds have been found in Arkansas including the Esperanza diamond found in 2015. But there is no commercial mining taking place the US at the present time.
How are Diamonds Cut?
Rough diamonds are rare. And they are the hardest known natural substance. But in their raw form they are remarkably unremarkable! It is only through the diamond craftsmanship of man that the full beauty of a diamond can be observed.
Early diamonds were crudely cut by polishing a few simple facets with crude tools. Today, modern technology allows us to design and cut diamonds with tremendous precision. By proportioning diamonds properly and cutting the facets in such a way that they are aligned in an array of perfect mirrors, a diamond can be optimized for light performance, delivering maximum brilliance, fire and sparkle.
Modern Light Performance Cut Grading
Diamond cutters have long understood good diamond design from trial and error. In 1919 Marcel Tolkowski published the first scientific paper on the subject of diamond cut, and he explained why certain proportion sets would result in the greatest brilliance and fire. His work was based upon mathematics as applied to the known behavior of light as it is reflected and refracted by a diamond.
Modern science has given us a much greater understanding of diamond light performance resulting in the release in 2005 of the first light performance cut grading system by the American Gem Society.
The Dawn of the Super Ideal Cut Diamond
The modern ability to design and cut a diamond with extreme precision, along with the ability to scientifically analyze its light performance, is today fueling our ability to push the boundaries of diamond perfection. The super ideal diamond is one that exceeds even the most stringent laboratory requirements for the Ideal Cut designation. The A CUT ABOVE® super ideal diamond is such a brand. With all of its exacting specifications and qualifications published, it is easy to see why these diamonds are considered the “best of the best” by international diamond experts and connoisseurs.
How are Diamonds Priced?
Diamond prices are based on the diamond 4C’s. Cut, Color, Clarity, and Carat. Due to increasing rarity, as diamonds increase in size, like qualities increase in price at exponential rates. Diamonds in the normal range of D-Z colors (colorless to slightly tinted) are relatively more common than exotic diamonds. Other diamonds contain trace elements of crystal lattice characteristics that cause them to be colored in different attractive hues such as yellow, pink and blue and green. These fancy colored diamonds can be exceedingly rare and expensive. Fancy color diamonds are graded much differently than diamonds in the normal range.
Anyone shopping for a diamond can find helpful information in this straight forward diamond buying guide that covers all the bases. Great as a primer for someone new to diamonds, there are also links to more detailed information for even the most advanced diamond enthusiast.
In addition to natural diamonds, in the 1950’s mankind first synthesized diamond in the laboratory. Today there is an emerging industry producing man made diamonds. They have the same physical properties as diamond, but are grown in highly controlled laboratory environments. Like rubies and sapphires before them, the cost of synthetic diamonds will likely fall rapidly over time and will find appeal in the market among those that want a cheap alternative to the natural gems.
While synthetic diamond producers today promote their product as preferable to natural diamonds for ethical reasons, an objective look at the substantial benefits to millions of people working in the natural diamond industry paints an entirely different picture. Synthetic diamonds will have a place in the jewelry industry in the years ahead, just as synthetic rubies and sapphires do today. But their value is NOT as an “ethical alternative” to natural diamonds.
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