CUTTING THE FAMOUS JONKER DIAMOND

Hawke's Bay Herald-Tribune, Issue 19, 6 February 1937, Page 9

CUTTING THE FAMOUS JONKER DIAMOND

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

^jpHOSE of you who may have seen the Jonker 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 L'azare 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 was an overworked prospector and farmer of 62, who had persevered for 18 years, always on the brink of fortune, but always poor. He had reached 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 work on bucket gravel^ some of which had been washed up by the storm. He found a dirtcrusted stone about the size of a hen's egg. When he rubbed it clean his eyes nearly popped out of their soclcets. He had found World Diamond Number One. That night the treasure was put in a stocking and tied round Mrs Jonker 's neck. She went to bed but did not sleep, and the men kept guard at the door of the poor hut with loaded revolvers. Jonker sold the rough gem to the Diamond Syndicate for a reputed £70,000. It went to London and was of course examined by the leading experts. Even before the. diamond reached London the well knowa American gem dealer, Mr Harry Winston, cabled for an option and himself reached London soon after the diamond. H« spont a month studying the stone comparing it with the Cullinan, the Kohinoor, and the other famous gCms. Upon purchasing it he was confronted with the question of who should cut it. The foreign experts presented their plans with models of the separate gems which they thought could be taken from it. In diamond cleaving there is no miadle ground. It is either done perfectly or the 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 whieh a small error is cleaving would do was beyond reclconing, 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 insure the cutting of the Jonker Diamond. It is the only case ,to my, knowledge where Lloyd's refused to insure something. Their 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 roughj full of flaws. I contrived to cut it into 15 stones, all of which were perfect except one and even that one sold for £10,000. 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 whose skill is not surpassed anywhere in the world.At no. time in my experience had. I been confronted with such a tremendous challenge as when Harry Winston submitted the Jonker Diamond to me- Everything about this a'stounding stone "was' extra-« ordinary. I studied it for months and it ;was a year before I was sure of its grain. Once I was almost on the verge of delivering the blow with the mallet when I noticed a microscopio bend in a slight surface crack or gletz. This threw all my calculations off at the crucial moment. There was one certain spot on the surface of the Jonker that indicated the currect plans for cleaving. I labo.riously reconstructed the crystallisation of the diamond and thus determined exaetly all the planes along which to cleave.

Finally when I was sure to the fraction of a millimeter, I knew that the elusive inystery of the Jonker Diamond lay at the mercy of a light tap of the mallet. Of all the great diamonds in the history of the world the Jonker is only the second to be cleaveci, the'first being the Cullinan. And one who has not see this operation, which combiues the d^fficulties of an engineering f eat with those of a delicate surgical operation, cannot appreciate the strain to which it subjects the operator. When Joseph Asscher cleaved the Cullinan Diamond he so feared that.a mistake might be too great a shock to his wealc heart and cause him to drop dead, .that he had a doctor and two nurses in attendance to xevive him. When he delivered the stroke successfully he sank into a chair with a gasp oi relief, was treated by the doctor, and spent three months in a hospital suffering from a nervous breakdown,

No ordinary instruments would accommodate the great Jonker for this operation and I construeted special ones. I "Sound only one small place where I could make a groove. One tiny slip would spoil the . groove and compel me 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 Bcratched 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 whieh is not unlike a carving knife except that its edge instead of being sharp is square.. This gives the maximum spreading force of a wedge. A specially construeted counterbalanced mallet was held above it, and my son and I knew that the light tap that would be given in the next second would ring down the curtain on complete failure or complete success. The blow was struck and the diamond fell apart exaetly as we had planned. Cleaving is only the first operation in the cutting up of a large stone. ^ While it can be accomplished only in the direetion of the grain, the second operation of sawing can be accomplished only across the grain. "Whereas the first cleavage took a fraction of a second, the first single sawing xequired five weeks of continuous work. The 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 maehines was large • enough to aecommodate the Jonker, and we had to rebuild one. The edge of the saw is not sharp, but is cuij square and - is covered with a mixture of diamond dust and olive oil. The diamond dust works into the phosphor bronze and acts as the cuttinj surface. After being sawed the separate pieces are cut and polished. For this they are set in a metal foundation and held against the surface of a revolving disc. This operation puts the f acets 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 the 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 gone into dnst. One might think it a mistake to break up a stone of such unprecedented quality, but it will be far more valuable in separate pieces than in one. 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 the future story of the Jonker Diamond no one can say. We can only hope that its career will not be attended by the bloodshed and sorrow that has surrounded so many great jewels, and that it will enhance the beauty of beautiful women for many centuries.