SYNTHETIC GEMS

Wairarapa Times-Age, 9 July 1938, Page 9

SYNTHETIC GEMS

MANUFACTURE OF DIAMONDS FINE QUALITY ACHIEVED. Close on the heels of reports from various centres of world gem sales, that the recession has been reflected in a lessened ability of the people to buy diamonds, comes information, through a report read before a meeting of the American Chemical Society, that a measure of success has been achieved in the manufacture of synthetic diamonds, says the “Christian Science Monitor.”

It will be a long time before the activities still under way in laboratories any serious commercial possibilities. But the fact that chemists have succeeded in making synthetic diamonds of fine quality once again draws back the curtains on the dramatic experiences of M. Henri Moissan, a professor in the Paris School of Pharmacy, and another physicist identified with less exactitude as “the resourceful Parisian dreamer, August Verneuil.” It was professor Moissan’s aspiration to be able to make diamonds. “Never mind Kimberley, and the Golconda,” he cried, full of faith in his own ability plus his bent in the direction of logic; “I’ll make your diamonds—out of graphite—out of the lead you use in your pencils.” “Forget the mines of Ceylon,” added M. Verneuil, who was interested in sapphires and rubies. “I’ll make your sapphires and rubies —out of oxide of alumina—or, if you wish me to speak plainly, out of mud." They were young men then. This was before 1890. They were convinced they had only to reduce to crystals two common substances —graphite and mud —and they would be able to produce such stones as would become legendary. So they began the task of trying to discover the immemorial secret of‘how to transmute something base into something sublime. Professor Moissan at first dissolved carbon by melting iron around it, on the theory that, to get crystals, one dissolves a substance, and lets the solvent evaporate. But when he broke the iron away he found —not crystals, but a curious, coarse carbon. Finally he tried another tack. He burned sugar and got pure carbon, and this he melted with iron. He put the mass into his oven, and pushed the heat up to 4000 deg. The iron melted; it steamed like water boiled in a pot; the furnace, which was built of limestone, began to melt;. sparks shot out from the crucible. He fished out the molten mass and plunged it into cold water. The shell of iron tightened on the kernel, exerting a prodigious pressure. The professor’s hopes revived. Cautiously he worked the shell of iron away until he got down at last to the kernel—and there it lay—a bit of crystallised carbon—gleaming like a white star—a diamond, counterpart worthy to be compared with a stone which mine slaves might toil for months to find in the blue gravel of South Africa. That was in 1894. Here was a manmade diamond. But it had drawbacks. It was but a fiftieth of an inch across. It cost more than any mined stone had ever cost to produce. And it was not a job whose processes of completion could readily be taught to anyone else. Meanwhile, M. Verneuil had fared somewhat better. He knew that the first man-made ruby had been produced in 1837 by a man named Gaudin. It was just a little ruby, hardly big enough to see with the naked eye. In 1877 others had been made by M. E. Fremy, and M. C. Fell, but they were tiny, too, and of no value for commercial purposes. But M. Verneuil stoked his fires, nevertheless. For 10 years he kept them hot, trying to make sapphires and rubies, which, chemically, resemble each other exactly. For a long while the only thing he produced was lumps of some substance which glistened little more than a clinker from a cold furnace.

But then he began to have some little success, and the great gem house of Heller and Son heard of him, and A. A. Heller sent for him, asking him to come and see him. “I would like you to see if you can make some sapphires and rubies that can be sold,” said M. Heller, and M. Verneuil finally consented to attempt the task. In 1910 Verneuil reached his objective, a process of making sapphires and rubies which has been changed only in details of technique. It was never to become an easy process, this turning oxide of alumina into sapphires and rubies which can be recognised as synthetic because they are more “perfect” than genuine stones.

Only synthetic sapphires and rubies are produced in commercial quantities, and' these differ from the socalled “reconstructed” gems, produced in 1885 by a man in Geneva, who put pieces of small ruby together to make single, larger rubies.