CUTTING THE FAMOUS JONKER DIAMOND

Manawatu Times, Volume 62, Issue 34, 10 February 1937, Page 16 (Supplement)

CUTTING THE FAMOUS JONKER DIAMOND

Months of Painstaking Preparation by the World’s Foremost Cutter were Necessary Before this £70,000 Gem Fell Apart Exactly as was Planned

'J'HOSE of you who may have seen the Jonlcer Diamond when it was on exhibition at the American Museum of Natural History (the only occasion on which the public were given an opportunity to view it), remember an irregular frosted crystal about 2} inches long and 1$ inches wide. Its weight was 726 carats or nearly half a pound Troy, writes Lazare Kaplan in “Natural History," New York. This diamond, unlike other large ones, had not a single internal flaw, only a few “skin" flaws.

The story of its discovery was like a tale out of a book. Jacobus Jonker w r as an overworked prospector and farmer of 02, who had persevered for 18 years, always on tho brink of fortune, but always poor. Ho had roached the depths of despondency over his future, when his luck turned. There had been a heavy rain storm and when it died down a native was put to w’ork on bucket gravely some of which had been washed up by the storm. He found a dirtcrusted stone about the size of a hen’s egg. When ho rubbed it clean his eyes nearly popped out of their sockets. lie had found World Diamond Number One. That night tho treasure was put in a stocking and tied round Mrs Jonker’s node. She went to bed but did not sleep, and the men kept guard at tho door of tho poor hut with loadod revolvers.

Jonker sold the rough gem to the Diamond Syndicate for a reputed £70,000. It went lo London and was of course examined by tho leading experts. Even before the diamond reached London the well known American gem dealer, Mr Harry Winston, cabled for an option and himself reached London soon after tho diamond. He spent a month studying the stone comparing it with the Cullinan, tho Kohinoor, and the other famous gems. Upon purchasing it he was confronted with the question of who should cut it. , Tho foreign experts presented their plans with models of the separate gems which they thought could be taken from it.

Iu diamond cleaving there is no middle ground. It is either done perfectly or tho diamond is ruined. Diamonds have grain like wood but offer far more complex problems, and to misjudge the grain is disastrous. In the case of the Jonker Diamond, the damage which a small error is cleaving would do was beyond reckoning, for the peerless quality and extra-ordinary size of this stone made it the most important diamond extant.

It is a common saying that Lloyd’s will insure anything, but they would not insuro the cutting of the Jonker Diamond. It is tho only case to my knowledge where Lloyd’s refused to insure something. Thoir refusal is indicative of the dangers.

Mr Winston had, a short while before, entrusted me with the cutting of the Pohl Diamond. This was an extremely imperfect gem of 286 carats in the rough,' full of flaws. I contrived to cut it into 15 stones, all of which were perfect except one and even that one sold for £IO,OOO. This achievement in cutting was one reason why Mr Winston thought of me in connection

with the Jonker Diamond. He knew further that I had trained a corps of craftsmen whoso skill is not surpassed anywhere in the world.

At no time in my experience had I been confronted with such a tremendous challcngo as when Harry Winston submitted the Jonker Diamond to me. Everything about this astounding stone was extraordinary. I studied it for months and it was a year before I was sure of its grain. Once I was almost on tho verge of delivering the blow with tho mallet when I noticed a inicroscopio bend in a slight surface crack or gletz. This throw all my calculations off at the crucial moment. There was ono certain spot on the surface of the Jonker that indicated tho currect plans for cleaving. I laboriously reconstructed tho crystallisation of the diamond and thus determined exactly all the planes along which to cleave.

Finally when I was sure to the fraction of a millimeter, I knew that the elusive mystery of the Jonker Diamond lay at tho mercy of a light tap of the .mullet. Of all the great diamonds in the history of tho world the Jonker is only the second to bo cleaved, the first being the Cullinan. And one who has not see this operation, which combines the difficulties of an engineering feat with those of a delicate surgical operation, cannot appreciate tho strain to which it subjects the operator. When Joseph Asscher cleaved the Cullinan Diamond ho so feared that a mistake might be too great a shock to his weak heart and causo him to drop dead, that ho had a doctor and two nurses in attendance to revive him. When he delivered the stroke successfully he sank into a chair with a gasp of relief, was treated by the doctor, and spent three months in a hospital suffering from a nervous breakdown,

No ordinary instruments would accommodate tho great Jonker for this operation and I constructed special ones. I fdund only one small place where I could make a groove. Ono tiny slip would spoil the groove and compel mo to abandon my whole plan for cleaving. You may well imagine that in this initial step, my son, Leo, and I exercised the greatest care. The groove was scratched deeper and deeper with a series of sharper and sharper diamond edges, so as to produce a clean V-shaped groove. Then a steel blade was inserted which is not unlike a carving knife except that its edge instead of Joeing sharp is square. This gives the maximum spreading force of a wedge. A specially constructed counterbalanced mallet was held above it, and my son and I knew that the light tap that would be given in tho next second would ring down the curtain on complete failure or complete success. Tho blow was struck and the diamond fell apart exactly as wo had planned. Cleaving is only the first operation in the cutting up of a largo stone. While it can bo accomplished only in tho direction of tho grain, the second operation of sawing can be accomplished only across tho grain. Whereas tho first cleavage took a fraction of a second, the first single sawing required five weeks of continuous work. Tho saw is a disc of phosphor bronze about four'inches in diameter and between. .005 and .002, of an inch thick. None of the standard diamond sawing machines was large enough to accommodate tho Jonker, and we had to rebuild ono. Tho edge of the saw is not sharp, but is cut square and is covered with a mixture of diamond dust and olivo oil. Tho diamond dust works into the phosphor bronze and acts as tho cutting surface. After being sawed the separate pieces aro cut and polished. For this they are set in a metal foundation and held against tho surface of a revolving disc. This operation puts the facets on the gems. It is only with masterly polishing that optimum brilliancy is obtained. The same composition of olive oil and diamond dust does the work. But tho wheels of porous steel are manufactured especially by a secret process that has been passed down for generations in one family in Belgium. The Jonker Diamond will make 12 separate gems the largest of which will be approximately 170 carats. Of the original 726 carats the final aggregate will total only a little over 400, approximately 300 carats having gono into dust. One might think it a mistake to break up a stono of such unprecedented quality, but it will bo far more valuable in separate pieces than in ono. In former times there was a market for single stones of great size among kings, queens, and princes, but the day of crown jewels has virtually passed. What will be tho future story of tho Jonker Diamond no one can say. We can only hope that its career will not bo attended by tho bloodshed and sorrow that has surrounded so many great jewels, and that it will enhance the beauty of beautiful women for many centuries.