The earliest diamonds were used in their natural crystal form. Cutting originated in Europe in the 14th century. The first cuts merely flattened the top of the octahedron (table cut). The rose cut was then discovered, and it was found that extra facets increased brilliance.
Cutting developed further in the 17th century. Extra facets were added to the Table Cut, leading to the Single Cut, the Mazarin Cut, the Old Mine Cut and the Old European Cut. The last two were early versions of the modern Brilliant Cut.
In 1919 a young Russian mathematician called Tolkowski worked out the theoretically ideal proportions for a brilliant cut diamond.
This became known as the Tolkowski or American cut. It was designed to give the best possible balance between brilliance and dispersion.
The Tolkowski cut was originally the basis of the GIA system of diamond grading. This involved the comparison of the actual weight of the stone with the weight the stone would have had, had it been cut to ideal proportions.
Today a diamond's proportions are evaluated according to more generally accepted parameters, and the cut is classed on a four-point scale:
The wonderful gem we call the diamond is many different things. It is the most enduring symbol of enduring love. It is the purest substance that occurs in Nature. It is the hardest natural material in the known universe, and so it is the essential component of countless modern industrial tools. Its name comes from the Greek word Adamas invincible, unconquerable or the master.
Diamond was first mined in India some 2800 years ago. We know that men did not at first regard it as a gem, but as a strange and shining stone with amazing properties which resisted all attempts to cut or fashion it. Its unique hardness gave rise to the belief that it possessed magical properties, conferring power, courage and virility on its fortunate owners. So, for more than 2000 years, its main use was as a talisman worn in its uncut state exclusively by kings and rulers.
When man first succeeded in cutting diamond in about the 14th century its legendary invincibility became suspect, and its importance as a talisman diminished. However, through cutting, its hidden beauty began to emerge, and its rule as the king of gems began.
The Indian deposits were virtually the only supplies of diamond in the world until the beginning of the 18th century. It has been estimated that India's entire production, during a period of about 2500 years, was mere 10 million carats or an average of 4000 carats per annum, which by today's standards is a negligible production rate. However, the Indian deposits did supply many of the world's most famous and romantic diamonds, such as the Koh-i-noor.
In 1725, diamonds were discovered in Brazil, and for 130 years that country remained the world's chief supplier. Then, in 1867, a 15-year old boy named Erasmus Jacobs found a shiny yellow stone on a farm named de Kalk on the banks of the Orange River and the rest is history.
This find led to the development of the South African diamond fields, to the discovery of the source rock of diamond, to the formation of De Beers and to the establishment of a marketing organization that today controls more than 80% of the world's rough diamond sales.
During this century major diamond fields have been located and exploited in Sierra Leone, South-West Africa now Namibia, Angola, Zaire, Tanzania, USSR, Botswana and Australia, while diamond sales now exceed 10 million carats per annum.
But what is diamond's origin ? How are diamonds made ?
Men have asked that question since they were first discovered. Two thousand years ago they were believed to be splinters of stars. Another old legend has it that Alexander the Great found their source in a valley so deep no human eye could see the bottom. But diamonds come from deeper within the earth than even the ancient storytellers imagined.
A De Beers advertisement promoting larger stones asks
"How would it feel to own a million years ?"
But diamonds are older than that by far. It has been possible to date the kimberlite pipes in which they occur their ages run from 60 million to 17 hundred million years.
Scientists think that the long, slow process of diamond's crystallization took place in molten rock or magma about 100 miles below the surface of the earth and under circumstances of tremendous heat and pressure. Eventually, the pressure of the magma began to crack and split the surrounding rock. When the cracks or pipes reached the surface the magma was forced explosively upwards with a violence most experts think may have cracked and cleaved many of the diamonds it carried with it including the Cullinan, incidentally.
On the way up the magma picked up other rocks and minerals, forming itself into the geological plum pudding we now call kimberlite, which formed volcanic craters on the earth's surface. Over millions of years these were gradually eroded away until they were more or less level with the surface of the earth. The diamonds, freed from their matrix or mother rock, were carried by running water to the beds of streams or rivers or the open sea, there to be deposited in beds or terraces.
There are therefore 2 main sources of diamonds: Primary deposits, which are the kimberlite pipes themselves, and secondary or alluvial deposits. Only about 20% of the world's diamonds are taken from pipe mines. The remaining 80% are alluvial. The same ratio applies to gem and industrial, or inferior quality diamonds. 20% of diamonds recovered are fine enough to be considered of gem quality; the rest are used in industry. (These may not be as beautiful, but they are extremely useful !)
The WEIGHT of a diamond is expressed in carats. A carat is one fifth of a gram. Diamond weights are usually given to 2 decimal places of a carat. One of the many puzzling facts about diamonds is that as mines get deeper the average size and number of stones found gets smaller. In fact, overall, larger stones are becoming increasingly rare as time goes by, and it is fairly certain that more diamonds have been taken out of the earth than remain to be discovered within it.
Diamond is crystallized carbon like graphite, out of which the lead in your pencil is made. The difference in the two forms of pure carbon is due to the very special arrangement of the atoms in diamond, which accounts for its unique hardness and also for its other special properties. It also accounts for a diamond having a grain, like wood, which makes it harder in some directions than in others.
On the Mohs scale of hardness, by the way, diamond scores 10, coming far and away on top of the hardness class. The result of this is that only a diamond will scratch another diamond no other material on earth is hard enough to do so.
When a diamond is cut and polished, its unique optical properties can be seen and appreciated.
Special points to note are, first, its LUSTRE. Lustre is the appearance of a surface as it reflects light. The less perfect the polish on a surface, the less perfect its lustre will be. Not surprisingly, the polished facets of a diamond have a lustre so perfect that It has a name all its own adamantine lustre: the lustre of a diamond.
In a well-cut diamond the BRILLIANCE, or the quality of light reflected from the surface and the interior of a stone when it is motionless and seen in the face-up position, is far superior to that of any other stone. We have all admired the property known as DISPERSION, which is more simply known as fire. It's actually what children call 'making rainbows' diamonds break up white light into its constituent colors: red, orange, yellow, green, blue, indigo and violet.