How Diamonds Are Polished

Processes to transform a diamond in the rough into the exquisite brilliant of commerce

diamond dop

The tools of the diamond lapidary’s art are very simple. The little metal cup or “dop,” in which the diamond is being placed, as well as the wooden holder which carries it, are of exactly the same shape as those used by the diamond cutters of a hundred years ago.

Suppose you were taking a walk somewhere in the middle of South Africa and, happening to glance down, saw at your feet a small, angular, irregular object, clear like glass but with a surface that looked as though it had been smeared with oil. You would probably kick it aside and proceed on your way; and yet this insignificant-looking thing might easily be a diamond of great value.

Diamonds as they are found in the rough state are not impressive. They have none of the magical flashes of light which in the finished stone make them unique among the noble family of gems. It is in polishing that a goodly part of the price of a diamond is acquired; for the art of turning a rough diamond into a glittering brilliant is a long process requiring a superlative degree of skill. There is no better way to appreciate this than to follow the diamond from the mine to the jeweler and see for ourselves just what happens to it.

When the diamonds are taken out of the mine, not by any means are all of them clear and colorless, as a self-respecting diamond should be; indeed only about 25 per cent of the stones found are without some faint color. Of the remainder about one third are of a light shade of color, such as violet, yellow, or brown, and are known as “off-color” stones. The remainder, roughly one half of the total find, are more or less deeply colored and are consequently of no value for jewelry although still usable for diamond cutting and polishing or for facings for rock drills. So we find that at the beginning of its travels the diamond is introduced to the sorter. The sorter is a kind of super-expert on diamonds whose eye has been trained through years of practice to detect the slightest variations in the color of diamonds and to find flaws in the stones with an ease which is little less than uncanny. Safeguarded behind a heavy metal screen, the diamond appraiser sits with a pile of rough stones before him, judging each stone and assigning it to its proper heap.

The first consideration in sorting diamonds is the adaptability of the stone for cutting. Let us assume that the stone whose travels we are following is sorted into the grade known as “close goods,” comprising complete, flawless crystals from which fair-sized brilliants can be cut or, to use the trade term, “made.” These usually have eight sides or faces, triangular in shape. Next comes a resorting of the “close goods” into eight grades, ranging from blue-white, which comprises the stones of finest quality, to yellow and brown, which are so badly off-color as to be unfit for gems.

Just the right amount of the stone, no more and no less, must be split away. The intent expression on the face of the operator bears witness to the momentous effect of the slight blow he is about to strike on the steel knife edge which he holds in his left hand. If our stone has passed the critical test of the sorter and has been placed in one of the higher grades, it is weighed, wrapped up in a parcel with others of its kind, a price per carat is assigned to it, and it is sold to a diamond dealer, and ultimately finds its way to the workshop of the diamond polisher. Here, at the hands of a highly skilled workman, it is destined to he turned into a gem fit to grace beauty or proclaim opulence.

Most of this work is done in Holland, and especially in Amsterdam, which since the fifteenth century has been famous for this industry, in reality an art, but there are, nevertheless, a number of shops in operation right here in our city of New York. Like many other operators who depend for their success on a high degree of manual skill the diamond cutter has few tools, and these are relatively primitive and have changed little since the days of Louis de Bequem, who cut diamonds in 1475. The lapidary depends like the violin player on the delicacy of his touch, and like the painter on the accuracy of his eye, and he scorns to use complex mechanical devices to aid him in his difficult task.

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