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LAPIDARY
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LAPIDARY , and See also:GEM CUTTING (See also:Lat. lapidaries, lapis, a See also: See also:Prior to this period, all the See also:work appears to have been done by See also:hand with a sapphire point, or else with a how-See also:drill; thenceforward the See also:wheel came to be largely employed. The See also: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 See also:hundred years. See also:Engraving by the See also:bow-drill was introduced in See also:Assyrian and Babylonian work as See also:early as perhaps 3000 B.C., the earlier carving being all done with the sapphire point, which was secured in a handle for convenient application. This hand-work demanded the utmost skill and delicacy of See also:touch in the artist. The bow-drill consisted of a similar point fastened in the end of a stick, which could be rotated by means of a See also:horizontal See also:cross-See also:bar attached at each end to a See also:string See also:wound around the stick; as the cross-bar was moved up and down, the stick was made to rotate alternately in opposite directions. This has been a frequent See also:device for such purposes among many peoples, both ancient and See also:modern, civilized and uncivilized. The point used by hand, and the bow-drill, were afterwards variously combined in executing such work. Another modification was the substitution for the point, in either See also:process, of a hollow See also:tube or drill, probably in most cases the joint of a hollow See also:reed, whereby very accurate circles could be made, as also See also:crescent figures and the like. This process, used with See also:fine hard See also:sand, has also been widely employed among many peoples. It may perhaps have been suggested by the See also:boring of other shells by carnivorous molluscs of the Murex type, examples of which may be picked up on any See also:sea-See also:beach. It is possible that the cylinder seals were drilled in this way out of larger pieces by means of a hollow reed or bamboo, the cylinder being See also:left as the core. The See also:Egyptian scarabs were an early and very characteristic type of seal cutting. The Greek gem cutters modified them by adding Greek and See also:Etruscan symbols and talismanic signs; many of them also worked in Egypt and for Egyptians. Phoenician work shows a mixture of Assyrian and Egyptian designs; and Cypriote seals, principally on the See also:agate gems, are known that are referred to the 9th century B.C. Scarabs are sometimes found that have been sliced in two, and the new See also:flat faces thus produced carved with later inscriptions and set in rings. This secondary work is of many kinds. An Assyrian cylinder in the See also:Metropolitan Museum, New See also:York, referred to 3000 B.C., bears such a cutting of Mediterranean See also:character, of the and or 3rd century B.C. In the early See also:Christian era, also, many Greek and See also:Roman gems were recut with Gnostic and other peculiar and obscure devices. In the later Roman period, the 3rd and 4th centuries, a great decline in the See also:art is seen—so great that Castellani terms it " the idiotic See also:age." See also:Numbers of gems of this See also:kind have been found together, as though they were the product of a single manufacturer, carved in the crudest manner, both in See also:design and See also:execution. Yet remarkable results are sometimes produced in these by a few touches of the drill, which under the See also:glass appear very crude but nevertheless yield strong effects. The same thing may be seen now in many of the See also:Japanese sketches and See also:lacquer designs, where a whole landscape is depicted, or rather suggested, by a few See also:simple but powerful strokes. It is now thought that some of these seals may be of earlier origin than has been supposed, and also that they may have been worn by the poorer classes, who could not afford the more finished work. They must have been made by the hundred thousand. The decline of the art went on until in the See also:Byzantine period, especially the 6th century, it had reached a very See also:low point. Most of the gems of this period show drill-work of poor quality, although hand-work is occasionally seen. With the See also: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 See also:judge positively as to the age of engraved gems. The materials of which they are made are hard and resistant to any See also:change through time, and there are many ingenious devices for producing the appearances usually believed to indicate great age, such as slightly dulled or scratched surfaces and the like. There are also the gems with secondary carving, already alluded to, and the ancient gems that have been partially recut by modern engravers for the purpose of fraudulently enhancing their See also:price. All these elements enter into the problem and make it an almost hopeless one for any but a See also:person of great experience in the study of such See also:objects; and even he may not be able in all cases to decide. Until the 14th century, almost all the gems were cut en cabochon—that is, smoothly rounded, as carbuncles and opals are still—or else in the form of beads drilled from both sides for suspension or See also:attachment, the two perforations often See also:meeting but imperfectly. These latter may be of See also:Asiatic origin, brought into See also:Europe by See also:commerce during the See also:Crusades. Some of the finest gems in the See also:Austrian, See also:Russian and See also:German crowns are stones of this perforated or See also:bead type. An approach, or transition, to the modern facetting is seen in a See also:style of cutting often used for rock-crystal in the loth and rlth centuries: an See also:oval cabochon was polished flat, and the sides of the See also:dome were also trimmed flat, with a rounded back, and the upper See also:side with a See also:ridge in the centre, tapering off to the See also:girdle of the stone below. The See also:plane facetted cutting is altogether modern; and hence the pictures which represent the breastplate of the ancient Jewish high-See also:priest as set with facetted stones are wholly imaginary and probably incorrect, as we have no exact knowledge of the forms of the gems. The Orientals See also:polish gems in all sorts of irregular, rounded shapes, according to the form of the piece as found, and with the one See also:object of preserving as much of its See also:original See also:size and See also:colour as possible. The greatest ingenuity is used to make a speck of colour, as in a sapphire, See also:tone up an entire gem, by cutting it so that there is a point of high colour at the See also:lower side of the gem. In later times a few facets are sometimes cut upon a generally rounded stone. The cabochon method is still used for opaque or translucent stones, as See also:opal, See also:moonstone, turquoise, See also:carbuncle, &c.; but for transparent gems the facetted cutting is almost always employed, on See also:account of its fine effect in producing brilliancy, by reflection or See also:refraction of See also:light from the under side of the gem. Occasionally the ancients used natural crystals with polished faces, or perhaps at times polished these to some extent artificially. This use of crystals was frequent with prismsof emerald, which were drilled and suspended as drops. Those the French See also:call " primes d'emeraudes." These were often natural crystals from Zaborah, Egypt or the See also:Tirol Mountains, drilled through the height of the See also:prism, and with little or no polishing. In rare instances perfect and brilliant crystals may now be seen mounted as gems. The modern method is that of numerous facets, geometrically disposed to bring out the beauty of light and colour to the best See also:advantage. This is done at the See also:sacrifice of material, often to the extent of See also:half the stone or even more—the opposite of the See also:Oriental See also:idea. There are various forms of such cutting, but three are specially employed, known as the brilliant, the See also:rose and the table-cut. The last, generally made from cleavage pieces, usually square or oblong, with a single facet or edge on each side, and occasionally four or more facets on the lower side of the stone, is used chiefly for emeralds, rubies and sapphires; the two former for diamonds in particular. The brilliant is essentially a low, See also:double cone, its See also:top truncated to form a large flat eight-sided See also:face called the table, and its basal See also:apex also truncated by a very small face known as the culette or cullet. The upper and lower slopes are cut into a See also:series of triangular facets, 32 above the girdle, in four rows of eight, and 24 below, in three rows, making 56 facets in all. 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 " See also:roses couronnees "; others with fewer facets, twelve or even six, are called " roses d'Anvers," and are a specialty, as their name implies, at See also: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. There are several other forms, among which are the " briolette," " marquise," oval and See also:pear-shaped stones, &c., but they are of See also:minor importance. The pear-shaped brilliant is a facetted See also:ball or drop, being a brilliant in style of cutting, although the form of the gem is elongated or drop-shaped. The " marquise " or " navette " form is an elliptical brilliant of varying width in proportion to its length. 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 See also:gauge are much used and are closely set together, forming a continuous See also:line of colour. Modern gem cutting and engraving are done by means of the See also:lathe, which can be made to revolve with extreme rapidity, carrying a point or small disk of soft See also:iron, with diamond-dust and oil. The disks vary in See also:diameter from that of a See also:pin-See also:head to a See also:quarter of an See also:inch. Better than the lathe, also, is the S. S. See also: The ancient garnets, from Etruscan and Byzantine remains, some of which are flat plates set in See also:gold, or carved with mythological designs, were probably obtained from India or perhaps from the remarkable locality for large masses of garnet in German East Africa. Many are cut with the portraits of Sassanian See also:kings with their characteristic See also:pearl earrings. The East See also:Indians carve small dishes out of a single garnet. The carving of elegant objects from transparent quartz, or rock crystal, has been carried on since the 16th century, first in See also:Italy, by the greatest masters of the time, and afterwards in See also:Prague, under See also:Rudolph II., until the See also:Thirty Years' See also:War, when the industry was wiped out. Splendid examples of this work are in the important museums of Europe. Many of these are reproduced now in See also:Vienna, and fine examples are included in some See also:American museums. Among them are rock-crystal dishes several inches across, beautifully en-graved in See also:intaglio and mounted in See also:silver with gems. Other varieties of quartz minerals, such as agate, See also:jasper, &c., and other ornamental stones of similar hardness, are likewise wrought into all manner of art objects. Caskets, vases, ewers, coupes and animal and other fanciful forms, are familiar in these opaque and semi-transparent stones, either carved out of single masses or made of See also:separate pieces See also:united with gold, silver or See also:enamel in the most artistic manner. See also:Cellini, and other masters in the 16th and 17th centuries, vied with each other in such work. The greatest development of agate (q.v.), however, has been seen in See also:Germany, at Waldkirch in See also:Breisgau, and especially at See also:Idar and See also:Oberstein on the See also:Nahe, in See also:Oldenburg. The industry began in the 14th century, at the neighbouring See also:town of See also:Freiburg, but was transferred to Waldkirch, where it is still carried on, employing about 120 men and See also:women, the number of workmen having increased nearly threefold since the See also:middle of the 19th century. The Idar and Oberstein industry was founded somewhat later, but is much more extensive. See also:Mills run by See also:water-See also:power line the Nahe See also:river for over 30 m., from above See also:Kreuznach to below Idar, and gave employment in 1908 to some 5000 See also:people—1625 lapidaries, 160 drillers, 100 engravers, 2900 cutters, &c., besides 300 jewellers and 300 dealers. The industry began here in consequence of the abundance of agates in the See also:amygdaloid rocks of the vicinity; and it is probable that many of the Cinque See also:Cento gems, and perhaps even some of the Roman ones, were obtained in this region. By the middle of the 18th century the best material was about exhausted, but the industry had become so firmly established that it has been kept up and increased by importing agates. In 1540 there were only three mills; in 1740, twenty-five; in 1840, fifty; in 1870, one hundred and eighty-four. Agents and prospectors are sent all over the world to procure agates and other ornamental stones, and enormous quantities are brought there and stored. The See also:chief source of agate See also:supply has been in See also:Uruguay, but much has been brought from other distant lands. It was estimated that fifty thousand tons were stored at See also:Salto in Uruguay at one time. The grinding is done on large, horizontal wheels like grindstones, some 6 ft. in diameter and one-See also:fourth as thick, run by. water-wheels. The faces of some of these grindstones are made with grooves of different sizes so that See also:round objects or See also:convex surfaces can be ground very easily and rapidly. An agate ball or See also:marble, for instance, is made from a piece broken to about the right size and held in one of these semicircular grooves until one-half of it is shaped, and then turned over and the other half ground in the same way. The polishing is done on wooden wheels, with See also:tripoli found in the vicinity ; any carving or ornamentation is then put on with a wheel-edge or a drill by skilled workmen. In the United States the See also:Drake See also:Company at See also:Sioux Falls, South Dakota, has done cutting and polishing in hard materials on a See also:grand See also:scale. It is here, and here only, that the agatized See also:wood from Chalcedony See also:Park, Arizona, has been cut and polished, large sections of See also:tree-trunks having been made into table-tops and columns of wonderful beauty. with a polish like that of a See also:mirror. Much of the finest lapidary work, both on a large and a small scale, is done in See also:Russia. See also:Catherine II. sought to develop the See also:precious stone resources of the Ural region, and sent thither two See also:Italian lapidaries. This led to the See also:founding of an industry which now em-ploys at least a thousand people. The work is done either at the great imperial lapidary See also:establishment at See also:Ekaterinburg, or in the vicinity of the mines by lapidary masters, as they are called, each of whom has his peculiar style. The products are sold to dealers at the great Russian fairs at Nizhniy See also:Novgorod, See also:Moscow and Ekaterinburg. The imperial works at the last-named place have command of an immense water-power, and are on such a scale that great masses of hard stones can be worked as marble is in other countries. Much of the machinery is See also:primitive, but the applications are ingenious and the results unsurpassed anywhere. The work done is of several classes, ranging from the largest and most massive to the smallest and most delicate. There is (1) the cutting of facetted gems, as See also:topaz, See also:aquamarine, amethyst, &c., from the mines of the Ural, and of other gem-stones also; this is largely done by means of the cadrans, a small machine held in the hand, by which the See also:angle of the facets can be adjusted readily when once the stone has been set, and which produces work of great beauty and accuracy. Then there is (2) a vast variety of ornamental objects, large and small, they are made from the opaque minerals of the Ural and See also:Siberia—See also:malachite, See also:rhodonite, lapis-lazuli, See also:aventurine and jasper. A peculiar type of work is (3) the See also:production of beautiful See also:groups of See also:fruit, See also:flowers and leaves, in stones selected to match exactly the colour of each object represented. These are chosen with great care and skill, somewhat as in the Florentine mosaics, not to produce a flat inlaid picture, however, but a perfect See also:reproduction of form, size and colour. These groups are carved and polished from hard stones, whereas the Florentine See also:mosaic work includes' many substances that are much softer, as glass, shell, &c. Enormous masses of material are brought to these works; the supply of rhodonite, See also:jade, jaspers of various See also:colours, &c., sometimes amounting to hundreds of tons. One See also:mass of Kalkansky jasper weighed nearly 9 tons, and a mass of rhodonite above 50 tons; the latter required a See also:week of sledging, with ninety horses, to bring it from the See also:quarry, only 14 M. from the works. About seventy-five men are employed, at twenty-five roubles a See also:month (L2, its. 6d.), and ten boys, who See also:earn from two to ten roubles (4s. to £i). A training school is connected with the works, where over fifty boys are pupils; on graduating they may remain as See also:government lapidaries or set up on their own account. There are two other great Russian imperial establishments of the same kind. One of these, founded by Catherine II., is at See also:Peterhof, a See also:short distance from the See also:capital; it is a large See also:building fitted up with imperial elegance. Here are made all the designs and See also:models for the work done at Ekaterinburg; these are returned and strictly preserved. In the Peterhof works are to he seen the largest and most remarkable achievements of the lapidarian art, vases and pedestals and columns of immense size, made from the hardest and most elegant stones, often requiring the labour of years for their completion. The third great establishment is at Kolyvan, in Siberia, bearing a like relation to the minerals and gem-stones of the See also:Altai region that the works of Ekaterinburg do to the Ural. The three establishments are conducted at large expense, from the private See also:revenue of the See also:tsar. The Russian emperors have always taken special See also:interest in lapidary work, and the products of these establishments have made that See also:country famous throughout the world. The immense monolithic columns of the Hermitage and of St See also:Isaac's See also:Cathedral, of polished See also:granite and other hard and elegant stones, are among the triumphs of modern architectural work; and the See also: Small balls are fixed in the end of a bamboo tube, which the worker continually revolves. The final brilliant polish is given by the hand, with See also:rouge-powder (haematite). This process is evidently very slow, and only the cheapness of labour prevents the cost from being too great. The spheres are now made quite freely but very differently in France, Germany and the United States. They are ground in semi-circular grooves in a large horizontal wheel of hard stone, such as is used for grinding garnets at Oberstein and Idar, or else by gradually revolving them on a lathe and fitting them into hollow cylinders. Plenty of water must be used, to prevent See also:heating and cracking. The polishing is effected on a wooden wheel with tripoli. Work of this kind is now done in the United States, in the production of the spheres and carved ornaments of rock-crystal, that is equal to any in the world. But most of the material for these supposed Japanese balls now comes from See also:Brazil or Madagascar, and the work is done in Germany or France. The cutting of See also:amber is a special See also:branch of lapidary work developed along the Baltic See also:coast of Germany, where amber is chiefly obtained. The amber See also:traffic See also:dates back to prehistoric times; but the cutting industry in See also:northern Europe cannot be definitely traced further back than the 14th century, when See also:gilds of amber-workers were known at See also:Bruges and See also:Lubeck. Fine carving was also done at See also:Konigsberg as early as 1399. The latter See also:city and See also:Danzig have become the chief seats of the amber industry, and the business has increased immensely within a recent period. Articles are made there, not only for all the cutters for centuries. Two See also:patents were taken out, however, by different parties, with some distinctions of method. The process is much slower than hand-cleavage, but greatly diminishes the loss of material involved. It is claimed that not only can flaws or defective portions be thus easily taken off, but that any well-formed crystal of the usual octahedral shape (known in the See also:trade as " six-point ") can be divided in half very perfectly at the " girdle," making two stones, in each of which the sawed face can be used with advantage to form the " table " of a brilliant. By another method the stone is sawed at a tangent with the See also:octahedron, and then each half into three pieces; for this Wood method a See also:total saving of 5% is claimed. Occasionally the finest material is only a small spot in a large mass of impure material, and this is taken out by most skilful cleaving. After the cleaving or sawing, however, the diamond is rarely yet in a form for cutting the facets, and requires considerable shaping. This rough " blocking-out " of the final form it is to assume, by removing irregularities and making it symmetrical, is called " brutage." Well-shaped and flawless crystals, indeed may not require to be cleaved, and then the brutage is the first process. Here again, the old hand methods are beginning to give place to mechanism. In either See also:case two diamonds are taken, each fixed in See also:cement on the end of a handle or support, and are rubbed one against the other until the irregularities are ground away and the See also:general shape desired is attained. The old method was to do this by hand—an extremely tedious and laborious process. The machine method, invented about 1885 and first used by See also: The hands must be protected with See also:leather gloves. The powder produced is carefully saved, as in the former processes, for use in the final polishing. When one face has been produced, the alloy is softened by heating, and the stone re-set for grinding another See also:surface; and as this process is necessary for every face cut, it must be repeated many times for each stone. An improved dop has lately been devised in which the diamond is held by a See also:system of claws so that all this heating and resetting can, it is claimed, be obviated, and the cutting completed with only two changes. 3. Polishing.—The faces having thus been cut, the last See also:stage is the polishing. This is done upon horizontal iron wheels called " skaifs," made to rotate up to 2500 revolutions per See also:minute. The diamond-powder saved in the former operations, and also made by crushing very inferior diamonds, here comes into use as the only material for polishing. It is applied with oil, and the stones are fixed in a " dop " in much the same way as in the cutting process. Additional information and CommentsThere are no comments yet for this article.
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