The Cutting And Polishing Of Gems

Albert Ramsay (Albert Ramsay & Co, 1925) writes:

The art of cutting precious stones can be traced back through the centuries. In 1285 a guild of gem cutters existed in Paris; about a century later there were lapidaries at work in Nuremburg and it is likely that the craft was followed long before this time. To Ludwig Van Berguen, of Bruges, is given the credit of first cutting diamonds with a symmetrical arrangement of facets. This was about 1460.

It is difficult to get precise information concerning the tools of the early gem cutters, but inasmuch as those of modern lapidaries are so very simple, it is probable that there has been little change in the instruments used in the trade. But while few changes mark the equipment of the modern lapidary, yet great strides have been taken toward greater skill and finesse on the part of the workers in the craft and the display of judgment that makes for getting the utmost in beauty and value from the rough gems.

In no other craft is the mental quality of judgment as important as in that of the lapidary. In the cutting of a valuable gem from the rough stone the slightest error in judgment may mean a vast difference in the beauty of the finished gem and a difference of many dollars in its value. Next to judgment the qualities that are of value in a lapidary are experience and skill and a trained delicacy of touch.

It will be interesting to the buyer of gems to know the routine of carrying the rough stone through the various processes that finally produce the finished polished gem as it is found at the jewelers. It may be well to explain here that the cutting and polishing of diamonds is a special craft—the lapidary who works in diamonds seldom concerns himself with other gems. It is also interesting to know that with the diamond to obtain brilliancy is the prime requisite, while with most other gems the matter of color is given precedence and brilliancy is a subservient quality.

The cutting and polishing of the diamond is very largely a mechanical, mathematical application of pressure and friction, while most other gems are manipulated with a human delicacy of touch and a perfection of technique which constitute the whole secret of success in gem cutting. The cutter of gems other than the diamond has a license for following his own ideas and he may alter or modify the cutting to bring out the peculiarities of any stone and depart as far as he wishes from the conventional. I shall describe here the various processes through which a rough gem stone passes.

The best judgment of the lapidary is called into play in his first consideration of the rough stone, for it is here that his experience and wisdom provides for getting the greatest measure of beauty and value from the uncut gem, and for minimizing waste and loss of weight. After passing upon the characteristic of a rough stone and deciding upon the method of getting the most from it, the lapidary, if the gem requires it, then puts it through the process known as ‘slitting,’ should this be required.

This process of dividing the rough stone is accomplished by holding it against the edge of a thin metal circular revolving plate. The biting edge of this plate is due to the diamond dust which it contains. The delicate operation of ‘slitting’ provides pieces of the stone in suitable sizes for further working. If the gem is to be faceted it is then further fashioned toward the shape it is destined to assume on a flat, horizontal or vertical revolving wheel. In order to facilitate handling each individual gem is then mounted with cement on the end of a tiny holder of wood. This holder looks very much like the ordinary pen holder. In this operation the extreme of judgment is required and considerable latitude is given the operator that he may bring out the individual characteristics and beauty of each gem.

After the faceting is complete the gem is still dull, colorless and uninteresting, and is now passed on to the polisher, whose work is to bring the utmost in brilliance and color to the surface of the gem. The polisher is usually a man who has no other connection with the gem than in polishing the work of the cutter. The work of the polisher is more mechanical than that of the cutter, but it is work of great delicacy nevertheless. The polisher must brighten and polish the facets, but in no way must he enlarge the tables or change the angles of the gem as designed by the cutter. The gem in the hands of the polisher may bring to light a number of faults—a tiny flaw may grow larger, an edge or angle may chip or a vein prove troublesome, and it requires a real craftsman, an operator with an exquisite nicety of touch, a man of infinite patience to carry the work of the cutter to completion and to do it with the least investment of time.

The discs used in polishing are similar to those used in cutting, except that instead of using an abrasive substance on the surface a variety of polishing materials, such as Tripoli or Rotten Stone is used. The discs used in both cutting and polishing are made of various materials, depending upon the peculiarities and hardness of the gem being handled. They are made of iron, brass, copper, lead, gun metal, bell metal, tin, pewter, etc. For polishing cabochon gems vertical wheels of copper, iron, wood, leather and felt are also used.