Gem cutting

“ An excursion into the literature of gems would reveal that there is much to be discovered about them other than the cold facts of gemology, techniques of gem cutting, and tales of gem lore. When all the information about an individual species is assembled, it provides a sketch of a fascinating gemstone personality. Whole books have been written about diamond—books filled with essays on its mining history, natural occurrences, scientific significance, and best known cut stones. ”

“ The “rondelle” form consists of flat, circular gems with smooth sides pierced, like shallow beads, with facetted edges, and is sometimes used between pearls, or gem beads, and in the coloured gems, such as rubies, sapphires, emeralds, &c. The mitred gems fitted to a gauge are much used and are closely set together, forming a continuous line of colour.
Modern gem cutting and engraving are done by means of the lathe, which can be made to revolve with extreme rapidity, carrying a point or small disk of soft iron, with diamond-dust and oil. ”

“ The cutting of gemstones, although sometimes tedious and time consuming, is not especially difficult or complex. However, like most arts and crafts, technique and ability should improve with practice and experience. There are currently many amateur gem cutters in Texas. ”

“ As the diamond perhaps shows more improvement on being cut than any other stone, and as the art of cutting the diamond is distinct from that of cutting other precious stones, both in the method of cutting and in the fact that the workers who cut diamonds cut no other precious stones, it will be well to consider diamond cutting separately. ”

“ Art of Cutting, Splitting, Sawing, and Polishing Diamonds [15] .
The object of cutting and polishing the Diamond is twofold. First, to divide the natural surface of the stone in a symmetrical manner, by means of a number of highly polished polygonal planes (facets) , and thus to bring out to the best advantage the wonderful refulgence of this beautiful gem; and secondly, by cutting away such flaws as may happen to be near the surface, to remove those blemishes that materially detract from its beauty, and consequently from its value. ”

“ THE process of diamond-cutting is a very simple matter to those acquainted with the nature of the gem. To cut the facets, two stones are cemented on two sticks, and rubbed against each other until a facet is cut ”

“ It is a singular fact that the external coverings of the mineral often contain the shades which render the rough gem of a disagreeable hue, and which may be made to disappear by the process of cutting. Therefore, it sometimes requires experience and tact to determine the value of a rough diamond which possesses a decided hue. However, those stones which exhibit a greenish or [Pg 258] reddish color are considered safe stones for investment, and will develop into superior gems after cutting. The bluish and the blackish are thought to be harder than the others ”

“ Before discussing the methods by which the shaping and polishing are accomplished let us consider briefly the object that is in view in thus altering the shape and smoothing the surface of the rough material.
How Cutting Increases Brilliancy. Primarily the object of cutting a diamond is to make it more brilliant. So true is this that the usual form to which diamonds are cut has come to be called the brilliant. The adjective has become a noun. The increased brilliancy is due mainly to two effects: First, greatly increased reflection of light, and second, dispersion of light. ”

“ Slitting and Cleaving. The cutting and polishing of precious stones other than diamond is a trade entirely distinct from diamond cutting. The precious stone lapidary cuts every species of stone except diamond. ”

“ Diamond cutting in the United States is now a well-established industry. From 1882 to 1885 a number of American jewelers undertook such work, but for various reasons it was not found practicable then. Ten years later, however, there were fifteen firms engaged in diamond cutting, giving employment to nearly 150 men in the various processes involved. In the year 1894 a number of European diamond workers came over; some foreign capital became engaged; and a rapid development of diamond cutting took place. ”

“ The tint must not be too light or too dark in shade: a stone that has barely any colour has little interest, and one which is too dark appears almost opaque and black. The lapidary can to some extent remedy these defects by cutting the former deep and the latter shallow. In certain curious stones—for instance tourmaline—the transparency, and in others—such as ruby, sapphire, and one of the recent additions to the gem world, kunzite—the colour, varies considerably in different directions. ”

“ After the facets are cut, and a [Pg 244] definite form given to the stone, the gem is placed in the hands of the polisher, who fastens it in solder, and then places it upon a small steel disk which revolves horizontally with a rapidity of 1,500 to 3,000 times a minute. This disk is moistened with diamond powder mixed with oil, and one facet is polished at a time. The diamond-cutting proper is a rapid operation; but the polishing is slow and tedious. One cutter can generally furnish sufficient work for four or five polishers. ”

“ Much skill is, therefore, required in cutting and [Pg 22] fashioning a precious stone, otherwise the gem may be ruined at the onset, for it will only divide along its lines of cleavage, and any mistake in deciding upon these, would "break," not "split" the stone, and destroy the beauty of its crystalline structure. An example of this was specially seen in the great Cullinan diamond, the splitting of which was perhaps the most thrilling moment in the history of precious stones. ”

“ Diamond is by far the hardest substance in nature, being marked 10 in Mohs’s scale of hardness, but it varies in itself; stones from Borneo and New South Wales are so perceptibly harder than those usually in the lapidaries’ hands, that they can be cut only with their own and not ordinary diamond powder, and some difficulty was experienced in cutting them when they first came into the market. ”

“ The date of about 500 B.C. marks the beginning of a period of great artistic taste and skill in gem carving, which extended throughout the ancient civilized world, and lasted until the 3rd or 4th century A.D. Prior to this period, all the work appears to have been done by hand with a sapphire point, or else with a bow-drill; thenceforward the wheel came to be largely employed. The Greek cutters, in their best period, the 5th and 6th centuries B.C., knew the use of disks and drills, but preferred the sapphire point for their finest work, and continued to use it for two or three hundred years. ”

“ It seemed strange that an artisan who possessed the rare ability to tell at a glance how large a gem the stone would cut, how to avoid internal imperfections, and how to take advantage of its cleavage planes, could not polish the facets after he had cut them. But such was the fact; for the two processes of cutting and polishing are widely different, and require separate instruction. However, the deficiency was soon supplied by an acquaintance, who was induced to leave Holland and act as polisher in the American diamond adventure. ”

“ It is true that we have no direct evidence of the cutting of the diamond in ancient times, and those that have descended to us from undoubted early Roman periods are in the shape of natural crystals; but still there is indirect testimony bearing in favor of the view.
The ancient gem engravers were wont to use splinters of broken diamonds in their labors upon various kinds of gems; and they probably powdered the adamas, as well as varieties of corundum, for the purpose of polishing the hard stones. ”

“ Sometimes but one color is visible in the stone, and then it is called emerald or golden opal, according to the tint exhibited.
The purchase of opals in the rough natural state is attended with danger, for often the glittering mass, after being shaped and polished by the lapidary, is transformed into a transparent but hueless stone. The cutting of the opal is always a hazardous operation, from the fragility of the material and the special tact required in determining the shape to be given the gem. ”

“ The cutting of gem-stones is explained under Lapidary.
The beauty and consequent value of gems depend mainly on their colour. Some stones, it is true, are valued for entire absence of colour, as diamonds of pure “water.” Certain kinds of sapphire and topaz, too, are “water clear,” as also is pure rock-crystal; but in most stones colour is a Colour. prime element of attraction. The colour, however, is not generally an essential property of the mineral, but is due to the presence of foreign pigmentary matter, often in very small proportion and in some cases eluding determination. ”

“ The modern method is that of numerous facets, geometrically disposed to bring out the beauty of light and colour to the best advantage. This is done at the sacrifice of material, often to the extent of half the stone or even more—the opposite of the Oriental idea. There are various forms of such cutting, but three are specially employed, known as the brilliant, the rose and the table-cut. ”

“ He opened a diamond-cutting establishment about 1860 and carried it on for some years, training a number of young men and women, who became the best cutters in the country. But the chief importance of his work lay in its superior quality. So long had it been a monopoly of the Dutch and Belgians that it was declining into a mere mechanical trade. Morse studied the diamond scientifically and taught his pupils how important mathematical exactitude in cutting was to the beauty and value of the gem. He thus attained a perfection rarely seen before, and gave a great stimulus to the art. ”

“ In this process, also, the old hand method is already replaced in part by an improved device whereby the diamond is held by adjustable claws, on a base that can be rotated, so as to apply it in any desired position. By this means the time and trouble of repeated re-setting in the dop are saved, as well as the liability to injury from the heating and cooling; the services of special “setters” are also made needless.
The rapid development of mechanical devices for the several stages of diamond cutting has already greatly influenced the art. ”

“ The rose form is used for diamonds not thick enough to cut as brilliants; it is flat below and has 12 to 24, or sometimes 32, triangular facets above, in three rows, meeting in a point. Stones thus cut are also known as “roses couronnées”; others with fewer facets, twelve or even six, are called “roses d’Anvers,” and are a specialty, as their name implies, at Antwerp. These, however, are only cut from very thin or shallow stones. None of the rose-cut diamonds is equal in beauty to the brilliants. ”

“ With the Renaissance, the art of gem carving revived, and the engravers from that time and onward have produced results that equal the best Greek and Roman work; copies of ancient gem carvings made by some of the 18th-century masters are only distinguishable from true antiques by experts of great proficiency. It is in fact extremely difficult to judge positively as to the age of engraved gems. ”

“ The leading position in diamond working still belongs to Amsterdam, where the number of persons engaged in the industry has trebled since about 1875, in consequence of the enormous increase in the world’s supply of diamonds. The number now amounts to 15,000, about one-third of whom are actual cleavers, cutters, polishers, &c. The number of cutting establishments in Amsterdam is about seventy, containing some 7000 mills. ”

“ The Spaniards formerly worked the mines by driving adits through the barren rock on the hillsides to the gem-bearing veins, but at the present day the open cut method of working is employed. A plentiful supply of water is available, which is accumulated in reservoirs and allowed at the proper time to sweep the debris of barren rock away into the Rio Minero, leaving the rock containing the emeralds exposed. Stones, of good quality, which are suited for cutting, are locally known as canutillos, inferior stones, coarse or ill-shaped, being called morallons. ”

“ While one can understand Ruskin's viewpoint, nevertheless the art of man can make use of the optical properties of transparent minerals, properties no less wonderful than those exhibited in crystallization, and indeed intimately associated with the latter, and, by shaping the rough material in accordance with these optical properties, greatly enhance the beauty of the gem.
No material illustrates the wonderful improvement that may be brought about by cutting [202] and polishing better than diamond. In the rough the diamond is less attractive in appearance than rock crystal. ”

“ In addition to the powder resulting from bruting, boart, i.e. diamonds useless for cutting, are crushed up to supply polishing material, and a little olive oil is used as a lubricant. Owing to the friction so much heat is developed that even the solder would soften after a time, and therefore, as a precaution, the dop is from time to time cooled by immersion in water. The stone has constantly to be re-set, about six being the maximum even of the tiny facets near the girdle that can be dealt with by104 varying the inclination of the dop. ”

“ When the love-sick Juliet queried ‘What’s in a name?’ her mind was wandering far from jewels; for them a name is everything. The beautiful red stones that accompany the diamond in South Africa were almost a drug in the market under their proper title—garnet, but command a ready sale under the misnomer ‘Cape-ruby.’ To many minds there is a subtle satisfaction in the possession of a stone which is assumed to be a sort of ruby that would be destroyed by the knowledge that the stone really belonged to the cinderella species of gem-stones—the despised garnet. ”