Cutting and Polishing Gemstones - A Collection of Historical Articles on the Methods and Equipment Used for Working Gems

By Read Books Ltd.

This book contains classic material dating back to the 1900s and before. The content has been carefully selected for its interest and relevance to a modern audience. Carefully selecting the best articles from our collection we have compiled a series of historical and informative publications on the subjects of gemology and crystallography. The titles in this range include "Gemstone Manufacturing" "The Optical Properties of Gemstones and Crystals" "The Thirty-Two Classes of Crystal Symmetry" and many more. Each publication has been professionally curated and includes all details on the original source material. This particular instalment, "Cutting and Polishing Gemstones" contains information on the methods and equipment of the gem cutter. Intended to illustrate the main aspects of cutting and polishing it is a comprehensive guide for anyone wishing to obtain a general knowledge of the subject and to understand the field in its historical context. We are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.

• Language: English
• Publisher: Read Books Ltd.
• Release date: Jul 7, 2014
• ISBN: 9781473395398

Book preview

DIAMOND CUTTING AND POLISHING.

The transcendent brilliancy of the diamond, its transparency and its refraction, are displayed very meagrely in rough stones. In order to render them susceptible of employment as personal ornaments, they must undergo the processes of cutting and polishing, which bring out the latent beauty in its true light; and, in fact, on the regularity of the facets and the perfect polish depends the value of the stone, nearly as much as on the original material; for, although no art can render a yellow brilliant white, still the purest stone, cut by unskilful hands, remains a dull mass, without life or lustre.

It is generally supposed that Louis van Berghem, or Berguem, was the first discoverer of the art of cutting and polishing diamonds by their own powder, in 1456; but this must be somewhat inaccurate, as already in 1373 the Emperor Charles had the clasp of his cloak ornamented with diamonds; and in church ornaments of even earlier date, were set diamonds with a table and four ground edges, and with the lower part cut as a four-sided pyramid.

In the inventory of the effects of the Duke of Anjou, made between the years 1360 and 1368, there is mentioned a diamond cut into the form of a shield. As yet, however, the mode of cutting was rude, and added scarcely at all to the lustre of the diamond, causing it to be ranked as less in value than many other gems.

In 1407, the art had made sensible progress under the direction of a clever artificer named Herman; and although the stones were still imperfectly cut, yet they must have had some lustre, as we find, that at an entertainment given to the King of France by the Duke of Burgundy, in 1410, the Duke of Burgundy gave away ten diamonds, which were valued at four hundred gold crowns a considerable sum in those days.

In 1456, Louis van Berghem, who had studied in Paris, discovered the art of cutting the diamond into regular facets; this discovery made so complete a revolution in the trade, that he was regarded as the parent of the art of diamond cutting, and he established in Bruges a guild of diamond cutters. In the year 1475 he made the first trial of his improved mode of cutting upon three large rough stones which were confided to his care by Charles the Bold, Duke of Burgundy. The largest was the stone known as the Sancy, which was lost in the disastrous fight of Granson; the second came into the possession of Pope Sixtus IV.; and the third, which was cut in the form of a triangle, was set in a ring, and was given to the faithless Louis XI. Robert van Berghem relates that his grandfather Louis received 3000 ducats for cutting these three stones. The pupils of Berghem established themselves in Antwerp and Amsterdam, leaving Bruges on account of the intolerance of the priests. Cardinal Mazarin patronized this industry greatly; he caused the diamonds in the French crown to be re-cut, and they obtained thence the name of the twelve Mazarins.

In the inventory of the French Crown jewels in 1774, the number 349 is described as the tenth Mazarin it is not known what has become of the rest.

The powerful protection of the Cardinal, and his example, caused a taste for these jewels to pervade all classes; and it is recorded that at this period Paris possessed seventy-five diamond cutters, who were well employed. Later, however, the trade declined, and from this date it seems gradually to have taken firm root in Amsterdam, where it still continues one of the principal branches of industry, and more than fifteen-sixteenths of the diamonds found are now cut there.

The so-called double cutting, Brillants recoupés, was introduced by Vincenti Peruggi, or Peruzzi, at Venice, about the end of the seventeenth century. In England there used to be several cutters, who were renowned for the excellence and perfection of their work, and whose diamonds, still called old English, fetch a much larger price than any others. As in everything else, however, the reduction of the price of labour produced a corresponding falling off in the quality of workmanship. This trade in England is now nearly extinct.

In India, where numbers of diamonds are still cut, the work is rough and defective, as the natives, with the mistaken idea of enhancing the value of their gems, leave them as heavy in weight as possible; often preserving the natural shape of the stone, and disregarding one of the first rules of diamond cutting, that over- as well as under-weight detracts from the value of the stone; and ignoring the fact, that a