UNDER PRESSURE cutting diamonds

 

I bet the the man who actually first laid eyes on the legendary jewel was not Frederick Wells (above). It seems unlikely that in South Africa in 1905 a white man would have been at the dig’s face, where the danger of a cave in was greatest.

Still, the legend has it that Frederick spotted the rock embedded in the stone wall just above his head (above, reenactment), reached up and pried what he first thought was glass out of the stone with his pen knife. And if that seems as unlikely to you as it does to me, we should both remember that everything about this particular stone is unlikely.

The nursery where this carbon crystal grew was an odd place. First, the surface above it had to have been stable for 1 to 3 billion years – maybe three fourths of the age of our planet. And for all of that time 90 to 120 miles below this stable surface the temperature had to be a constant 1,000 degrees centigrade, and the pressure about 653,000 pounds per square inch. The longer a carbon crystal remains under that pressure and temperature, the larger the crystal grows. And this one grew to weigh one and a half pounds. 

There are only a few spots in the earth where the temperature and pressure has remained consistent for so long; beneath the Canadian Shield, beneath Russian Siberia, beneath the Baltic Shield, beneath the southern tip of the Indian subcontinent,  beneath the Brazilian Shield, beneath northwest Australia, Beneath West Africa and beneath South Africa.

The heat allows the molecular bonds of carbon atoms to become plastic, while the immense pressure squeezes them into an eight sided crystal. Over eons such carbon crystals grow slowly and they must be fairly common in regions of the mantle where the carbon bonds with water. But then something unlikely happens. The earth burps.

If one of these carbon crystals rises to the surface slowly, over decades, the atoms binding its carbon molecules together return to their fail-safe state, which is graphite – pencil lead. 

For carbon to remain a crystal, it must reach the surface in a burst, over no more than a few minutes. To travel from the nursery to the surface, then, the stone must reach speeds of several hundred miles an hour. Supersonic.

Such a speed can only be reached if the capping pressure is suddenly punctured by a narrow fissure, at which point the temperature and pressure produces a powerful volcanic explosion at the surface. For that to happen is unlikely. But over four billion years unlikely becomes inevitable.

The first European who “owned” the surface above this particular jewel was a white immigrant farmer named Cornelis Minnaar.  His farm was in the southern part of Africa, north of the River Valaal, 25 miles east of the city of Pretoria (Tshwane).  The Boers, as these Dutch transplants called them selves, had made the trek to this region to avoid the British, who were intent on stealing their colony. 

In 1861 Cornelis sold a section of his land to his brother, Roelof , who in 1896, sold an even smaller part to Willem Prinsloo (above) who was just starting a family. The sale price was 570 English pounds, and it was William who owned the land when another Dutchman named Fabricus arrived looking for buried treasure.

Being experienced in this sort of thing, Fabricus first inquired as to where the Prinsloo households had dug their “sanitary pits”. This was a euphemism for the holes used to bury the products of your outhouse, politely known as “night soil”. Why dig a hole when a hole had already been dug? But since to date nothing unusual had been found in the sanitary pits, Fabricus assumed he would have to look elsewhere. 

Once he had located some “virgin dirt”, he scrapped away the thin red top soil, and then hacked his way through ten feet of yellow limestone gravel (above), the bi-product of primordial coral reefs...

...before reaching a blue slate gravel (above) peppered with tiny red garnets. This rock was called Kimberlite.  And when he saw it, Fabricus realized he had struck pay dirt

Fabricius was working for an Englishman named Henry Ward, who had paid for the option to search on Prisloo’s land.  But Ward didn’t have the money to make the buy, and besides William Prisloo (above) was not interested in selling to an Englishman, since it looked like war was about to break out between the Boers and the English. 

Which it did.  Two of them, in fact.  After the second war was finally settled in 1904 – The British won – Ward now sold out his options to Thomas Major Cullinan.  

By then Willem Prinsloo was dead. So Thomas Cullinan (above) made an offer to William’s widow, Maria Prisloo.  Broke and defeated, she sold the farm for 52,000 pounds. Not a bad profit.

Cullinan and partners named their new venture "The Premier Mine". Production started at the end of April 1903, and in a year 2,000 people, mostly local Africans were blasting, chopping, digging and hauling blue Kimberlite out of the open pit. They were looking for diamonds.

Most diamond mines start out as open pits. A Kimberlite Pipe is famously “carrot shaped”, wide at the top, narrow towards the bottom. And after less than a year of digging, on 25 January, 1905, this new mine is credited with producing the largest gem quality diamond ever found.  

Diamonds are not rare, but gem quality diamonds are. On average two hundred tons of ore must be culled for every 1 caret of gem diamond, (there are 141.7 carets in every ounce) and only one out of every five million diamonds weighs two carets or above. 

The one and one half pound diamond Mr. Wells claimed to have pulled out of the rock face that January afternoon, was rated at 3,106 carets. In the name of good publicity, it was named after Mr, Cullinan.

After a nondescript voyage to England via the royal mail in an unmarked plain brown box, The Cullinan, as it was now known, was presented to King Edward VII. He asked as many experts as he could find - geologists, gemologists and even the physicists Sir William Cookes (above) -  how to cut this hunk of rock.

Cookes noted that around a small black spot in the interior of the stone the colors were very vivid, changing and rotating round the black spot.  "These observations indicated internal strain…there was a milky, opaque mass, of a brown color, with flakes of what looked like iron oxide trapped as the crystal formed around it.  There were four cleavage planes of great smoothness and regularity.” At issue was how to turn this indescribably rare nondescript lump into something indescribably rare and beautiful.

Diamonds had been known by Europeans since the tenth century, but it was not until the 17th century that they became popular amongst the aristocracy, not until the first “Brilliant Cut” by Italian jeweler Jules Mazarin, really showed the beauty that was hiding inside. His diamonds sparkled with 17 facets, or faces, each one reflecting light back out at the viewer. By 1900 the skill of the diamond cutter had increased the possible reflections to 57 facets.

The general consensuses was that the best cutter for this job was Joseph Asscher (above), ironically another Dutchman. He studied the Cullinan for six months in his shop in Amsterdam, surrounded by a small crowd of bankers, experts and royal representatives, laying out a plan of attack.

As the London Evening News reported in mid-January, of 1908, “…a special model of the diamond in clay was made…It was cut into pieces to give an idea of what would happen if the genuine stone were treated in the same way. After several experiments a definite plan was arrived at…”

Finally, on Monday, 10 February, 1908, at 2:45 pm, Joseph was ready. Surrounded by a small crowd of anxious interested third parties, Joseph poised his hammer over the chisel (above), the blade of which was lodged against the precise point which he had calculated the first strike had to be made. If he missed, or struck a glancing blow, the one-of-a-kind diamond worth a million pounds would be rendered damaged and might end up being worth a few thousand. Joseph drew a breath, and sharply struck the chisel….which cracked apart against the diamond.

Immediately Joseph ordered the room cleared, except for the notary republic for the bankers, who were financing this entire thing. Joseph checked the Cullinan and found it, thankfully, undamaged. He checked his tools (above), re-examined his plans and announced a week's delay while he fashioned a new, larger, chisel.

So it was that on 17 February, 1908, alone in the room with the diamond and the notary, Joseph lined his hammer up for a second time over The Cullinan. He struck the precise strong blow, directly above the dark inclusion...

...And the diamond fell apart into three perfectly clear pieces. Despite legends to the contrary, Joseph did not faint. He did, however, drink a glass of Champagne.  Eventually the Cullinan was cut into nine large stones (above)....

....and 96 smaller diamonds, so many that it took 8 months just to polish them all. 

And if you ever get to the Tower of London, you might make a note that the Crown Jewels of England on display there, (including the Queen Mother's broach, above)   might be literally billions of years old, but they have only been in the English royal families’ possession for a little over a hundred years. And they will always be a testament to the creation of timeless beauty under pressure.

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