Inherent Qualities Of The Diamond And Diamond Cutting
( Originally Published 1911 )
THE qualities which make a diamond so supremely beautiful are those which husband and coquette with light. As trembling dewdrops, restless waters, or the windows of a far-off cottage, receive the sun's rays and signal his glory far and wide with their flashlights, so the diamond makes an altar for the light of the atmosphere. But the water is unstable and the light of the window is evanescent; the diamond is everywhere and always ready for a single ray or the flood of noon. If a nimble ray glides over its surface, yet more swiftly does the diamond catch it in the passing, and breaking it into many, sends them on, a sparkling shower. Harder than all else, its glistening walls nevertheless give cheerful entry to the light, but exit, if properly cut, only where it entered. Once within, the adamantine faces smile and smile and pass it on, to cast it forth finally, effulgent. It is very wonderful that a thing can be at once so pervious and so impervious.
Light falling vertically upon the surface of a diamond, enters and passes on in a straight line, but of that which strikes it in a slanting direction, part is reflected and part enters. That which enters is refracted or bent. This is a power peculiar to mediums more dense than air. All precious stones possess it, but it is greater in the diamond than in any other. For instance, the indices of refraction for spinel and garnet, which are also, like the diamond, singly refractive stones, are 1.71 and 1.77; that of the diamond is 2.43.
To obtain the index of this refraction, draw a line perpendicular to the surface of the body through the point of entry of the ray, and a circle around with this point as a center. A straight horizontal line from the point where the circle intersects the ray, to the perpendicular line, is the sine of the angle of incidence, and the sides of the angle follow the ray and the perpendicular line to the impinging point as a vertex, thereby forming the angle of incidence. The ray on entering the body is bent or refracted toward the perpendicular line. The point in the circle, therefore, within the body, where it is intersected by the refracted ray, would be nearer the perpendicular line, on the other side of it. A line drawn between these two points would be the sine of the angle of refraction and with the sides forming a vertex at the central point with the vertex of the angle of incidence, would be the angle of re-fraction. It is the comparative lengths of these sines which give the index of refraction. In water it is as 1.33 to 1; in spinel 1.71, in garnet 1.77, and in diamond it is as 2.43 to 1.
The light, which falling upon the surface of the diamond is sent flashing on, constitutes the surface brilliancy, and that which finds entry, by the gem's power to hold and return it, forms the internal brilliancy.
The light which has entered the stone is now in the grip of more exacting laws. It has lost the full freedom of the air. The denser medium sets bounds, and the artisan knowing these, so cuts the diamond as to leave no avenue of escape for the entrapped light but the front of the gem where it entered. Jumping from wall to wall of the transparent enclosure, the rays try them all with points of light in vain, until they reach again the gate of entry, and even this must be properly approached if they would pass through.
The reason of it is this: that ray of light traversing a denser medium, in its efforts to escape back into the rarer medium, air, meets with an obstacle called " total reflection." Though light may in some degree enter from the rarer to the denser medium at any angle, it can return only within certain bounds.
Inside the limits of freedom, light passing from the diamond in a slanting direction into the air is also refracted as it passes the surface of the stone, but in a contrary direction. It is then bent pr refracted from instead of toward the perpendicular, and the sine of the angle of incidence is less than that of the angle of refraction. The direction of the ray is a simple reversal of that taken on entering the stone. The angle of total reflection is variously given as 24° 13' to 24° 24'. A ray of light impinging on the inner surface of a diamond slightly within or less than this angle, will on passing through to the air be refracted so that it will pass along the stone near the outer surface, as a brilliant shot of light. But if the ray falls upon the inner surface at a greater angle or more obliquely, it will be totally reflected; no part of it can escape into the air. It is for this reason a diamond is shaped and proportioned as it is now. Light entering the face of a properly-cut diamond reaches the back facets at angles of total reflection. Sent on according to the laws of light at the same angle as that of the incidence, they pass through the body of the stone to meet again angles of total reflection, and are again carried on until they emerge finally from the front of it. Look into the face of a diamond and you will see the imprisoned light scintillating on the burnished facets at the back. Turn it as you will and wherever you look, there is the sheen of light playing over transparent walls, adamantine to it ; an imprisoned star beneath a covering of limpid dew.
High refractive power is accompanied by a corresponding power of dispersion, consequently the dispersive power of the diamond is much greater than that of most mediums. It is as .058 to .021 in glass. In the re-fraction of a ray of white light, it is really broken into its constituent color rays, which are spread out spectroscopically. The index of refraction given is the mean of the color band. To this high power of dispersion is due the effect of color coming to the eye with the emission of flashlights of white light which has traversed the stone and been split up into its constituent colors, by refraction. Many expect to see this color play from the diamond under any light but sunlight and some artificial lights only are the source of it. Nor is the eye always sufficiently quick to catch it, though an illustration can be made, by holding a diamond to receive the sun's rays, and a sheet of paper at the proper angle to catch them as they are reflected by the stone. Then the brilliant rainbow colors will appear.
As the diamond crystallizes in the isometric system, in which the axes are equal, the refraction is normally single, though occasional stones, from extraordinary causes, are found to be doubly refractive. This means that a ray of light on entering the stone is split and refracted at two different angles.
What might be termed the reënforcement of the diamond's brilliancy is its hardness. It is brilliant because it is hard, and it remains brilliant for the same reason. Other stones by the wear and tear of contact become scratched, and their corners are roughened, but the diamond, year after year and generation after generation, remains undimmed. The hardest of all things, wearing does not mar its smooth facets and sharp corners. It laughs at the rough hand of time. Some years ago a German mineralogist named Moh arranged a scale, since known as Moh's scale, giving the relative hardness of various minerals, from talc, the softest, to diamond, the hardest. He made ten divisions as follows :
1. Talc, common foliated variety.
These minerals were selected because they are constant in the quality of hardness and reach in steps, from the softest to the hardest; but the difference of degree between them does not correspond with the ratio of the numbers. For instance, the hardness of emerald is given as 7.5 to 7.8. That means that its hardness is half way or more between quartz and topaz, but the difference between 7 and 8 is not nearly as great as between 9 and Io. It is said that the difference between 9 and 10 is greater than it is between 9 and 1. The scale therefore does not represent exact and absolute degrees of hardness, but is an arrangement of minerals of different degrees in that quality, numbered for convenient reference.
Nor is the diamond always of the same degree of hardness. Stones from wet diggings are usually harder than those from dry diggings. African diamonds are softer than Brazilians; Indian are harder, and those of Borneo and Australia are said to be hardest of all. The " nyf " or skin of a crystal is harder than the interior, and frequently there are knots in the grain, so much harder that it is difficult to cut them. Cut with or against the grain of a diamond, and the wheel makes little impression; it must be cut across the grain. Sir William Crookes is reported to have said of the Koh-inoor, that in cutting one of the facets near a yellow flaw, the crystal became so much harder the further it was cut, that after working the mill for six hours at the usual speed, little impression was made, and that the work proceeded very slowly even when the speed was increased to 3,000 revolutions per minute. Other portions of the stone were comparatively soft, but became harder as the outside was cut away.
The only rival of the diamond in hardness is the metal tantalum, of which it is said that in the effort to bore a hole through a plate of it, a diamond drill driven at the rate of 5,000 revolutions per minute for three days and nights, made a depression 1/4 mm. deep.
It has long been known that some diamonds absorb light. Robert Boyle in 1664 described this property of shining or phoshorescing in the dark, after being exposed to the sunlight. Late experiments have again demonstrated this peculiar power. The same result is obtained by exposing diamonds to a high-tension current of electricity in a vacuum, the light produced being of different colors, though South African stones emit in a majority of cases, a bluish light. Exposed to radium, diamonds glow with varying degrees of light and in various colors. Colorless crystals which Sir William Crookes kept embedded in radium bromide for a period of 12 months, were found to have assumed a bluish tint which resisted both fire and acids. They had also become radio-active, and heating to dull redness did not destroy the acquired power. Diamond is transparent to the X-rays, while glass is practically opaque.
The somewhat general idea that this quality of shining in the dark is common to all diamonds is an error founded on the statement by careless educators, of the truth that some do so. Isolated cases have been mentioned in such a way that they have been understood as typical, and some descriptions of phosphorescent stones have been quite imaginative. Reading in a dark room by the light of a phosphorescent diamond is so rare that no person other than the narrator would be likely to meet with a similar case. Experiments show that very few diamonds, either by exposure to sunlight or rubbing, will show any light in a dark room.
The diamond is ranked as a non-conductor of electricity and though, on rubbing, it becomes positively electrifled, it retains the charge for a very short time only; never more than half an hour.
The diamond is infusible, and is unaffected by acids and alkalies, but it burns in oxygen under intense heat to carbon dioxide and leaves no residue.
Though very hard, it is also very brittle and can be easily crushed to powder. It has a very perfect cleavage, separating readily parallel to the faces of the octahedra. The fracture is conchoidal or curved.
Hardness, 10 Moh's scale.
Specific gravity, 3.52.
Singly refractive (index, 2.439).
Reflective. Total reflection from inner facets at 24° 13° to 24° 24°.
Dispersive (dispersive power, 0.058)°.
Burns in oxygen at 4,000°.
Because of its hardness, the art of cutting the diamond as it is now cut, was acquired only after centuries of experiment. The ancients wore their diamonds uncut. Not as a matter of choice, for they knew them only in that form. They did not cut them because they could find nothing hard enough to make any impression upon the obdurate though beautiful stones. With Oriental philosophy they accepted the crystals as Nature made them and were satisfied. To-day even, well-formed crystals, or " Naifes," as they are called, are prized in India. Some thousands of years ago, however, it probably occurred to an observant Oriental that the stone might be turned against itself to smooth the rough places which marred the symmetry and brilliancy of many of the crystals. From that time hackl'd stones were improved by rubbing or grinding one against the other, and smooth places were made in lieu of natural facets. This was called " bruting," and the process was continued for centuries, even till long after the art of cutting them was established, in the grinding down of the crystal in preparation for the wheel, at the point where the main front facets would be.
The exterior of a diamond crystal is not brilliant like that of a cut diamond, but though hard looking and luminous, it has somewhat the appearance of a piece of alum. The " nyf," as it is called, looks like a dull skin over a brilliant body, so that if it has not always the luster of a quartz crystal even, there is something about it which attracts the eye and unmistakably differentiates it from all other stones. It is sometimes rough, but one sees at once that the roughness covers peerless qualities.
It is curiously illustrative of the Oriental character that with a knowledge of the diamond extending over many centuries, they got no farther in the art of improving the diamond than bruting. The art of cutting and polishing diamonds was discovered in Europe and perfected in the United States of America. It was a Venetian who cut the Great Mogul for the Hindu Prince, after whom, as the head of a dynasty, it was named. It is said there were diamond polishers in Nuremberg in the latter part of the fourteenth century, but the method of cutting them by grinding with their own powder is generally credited to Ludwig van Berquem or Berghem, also known as Louis de Bequem, of Bruges, who is said to have first done so in 1456. Bruges at that time was at the height of its prosperity under the dukes of Burgundy, and the industry continued there until, in the days of the city's misfortune and decadence, it was transferred with others to Antwerp. It flourished there until the Duke of Parma took the city in 1585. This was the ruin of Antwerp. Her commerce declined ; her inhabitants were scattered, and the Dutch, profiting by her misfortunes, did what they could to prevent her recovery. Diamond cutting was driven largely with other industries to Amsterdam, which has since become the chief center of the industry. The cutters of Antwerp nevertheless maintained a good reputation, and some of the Crown jewels of France were cut there during the eighteenth century. With Napoleon in the beginning of the nineteenth century, the fortunes of the city began to mend, and the diamond-cutting industry there improved, until the beginning of the twentieth century found it more flourishing than in the former palmy days.
There were 75 diamond cutters in Paris in 1700, but most of them were driven later by political troubles to Antwerp, and comparatively little cutting has been done there since.
Diamond cutting as an industry of importance in Amsterdam was founded by Jewish cutters from Lisbon. Their forefathers are said to have come originally from Alexandria. In Lisbon they brought the art to a high state of perfection for those days, but religious persecution, by driving them out of that city in the latter part of the sixteenth century, transferred the industry to Holland.
In the first step toward our modern cut brilliant, the paramount idea of the cutter was, to polish the surface of the crystal with a loss of weight only that was necessary to secure a smooth surface. To get more of the reflective power of the stone on the face of it, as a further improvement, he ground off the apex of the octahedron to a flat facet, making what we now call the " table," and took the tip off the corresponding point. This gave a square jewel with a large and a small flat facet parallel to each other, and from each of which four sloping facets spread to meet at the edges of the square, ten in all. To yet further increase the surface reflections of the stones, the corners of these sloping facets were ground off, thereby forming on top, four equal pentagonal facets extending from the central flat facet to the corners of the square, and four shaped like a keystone between them, extending to the sides. This arrangement changed the shape of the flat facet from a square to an octagon. The under side facets were cut to correspond, so that with the two flat facets there were eighteen in all. The large flat one on top was called the " table," the smaller one underneath, the " culet," and the others the " side facets." The space between the table and the girdle came to be known as " bizel," and that between the girdle and the culet, the " pavilion or " collet side."
From these primitive forms there was a gradual addition, in the effort to increase dispersion of the light rays, to the number of facets, and a tendency toward the rounding of the finished stone. Material improvement was slow, however. Large stones were scarce in those days, and the aim of the cutter was to produce as large a finished diamond from the crystal as possible. The added brilliancy arising from an increase in the number of facets, gradually forced the necessary sacrifice of material, and they were increased to thirty-four, variously arranged. Some of the old square cut brilliants had as many as fifty. Then came the English round-cut brilliant, having a triple row of star, main and corner facets between the table and the girdle, and a double row of corner and main facets from the girdle to the culet; thirty-two and the table above, and twenty-four and the culet below the girdle, in all fifty-eight facets. This arrangement remains in the perfect modern cut, for though further experiments have been made, nothing more excellent has been devised.
During all these years and stages of improvement, the cutter did not get beyond the idea of surface brilliancy and size. Some even then thought the small sacrifice of material necessary to obtain the facets, a foolish fad. They deplored it as a tendency to sacrifice magnificence to mere glitter. Yet the cut stones were thick and lumpy and good in shape only when the crystals favored them. But as the " brilliant " faceting prevailed, so also the round shape met with public approval, and the old square-cut stones became things of the past.
The cutting of the diamond had now reached a stage wherein full advantage was taken, by the number and arrangement of the facets, of the surface power of the stone to reflect and disperse the light rays falling upon it, and incidentally, to return part of the light entering the stone, to the eye, but the amount of the gem's internal brilliancy depended largely upon the shape of the rough. Although the surface brilliancy of a polished diamond is very great and beautiful, many of its dazzling flash-lights come from the interior. By taking advantage of the angle of total reflection, light coming into the stone and striking the interior back facets, cannot pass through, but is sent on at the angle of incidence, and finally returned in full measure through the face of the diamond to the eye of the beholder. It is these rays which are so preeminently beautiful in the diamond, and which fill the whole body of the stone with light. The surface sparkles ; the interior emits flashes. It remained for an American cutter, Mr. Henry D. Morse, of Boston, to make the daring sacrifice of weight to proportion necessary to attain the perfection of the modern brilliant. Disregarding the European method of cutting for weight, he did not hesitate to sacrifice material to make the finished stone as perfect and beautiful as possible. His work was appreciated. The public seeing the superiority of diamonds cut after his method, demanded them, and as the United States became the greatest buyer of diamonds in the world,, the cutters of Europe were obliged to conform more and more to the American standard, until it was adopted everywhere, and though naturally all diamonds are not cut on absolutely correct lines, they must now, to be salable, be cut to proportions which will secure the internal angles of total reflection. These proportions are within certain limits variable, but will approximate a depth from table to culet of 6/10 of the diameter, of which about one-third should be above the girdle and two-thirds below. A little less than one-third of the depth on top, if well cut, gives a sharper brilliancy with less weight.
The " brilliant-cut " diamond resembles two cones united at their bases, the upper one truncated or cut off a short distance from the base, and the lower one having the apex only cut off. It has fifty-eight facets altogether; an eight-sided flat facet on top, from which spread eight triangular star facets, called top corner facets. The points of these meet the points of sixteen split triangular facets whose bases rest on the girdle. Between these " lower corner facets " and the top corner or star facets, are eight lozenge or main facets whose points reach from the table to the girdle; altogether thirty-two side facets and the table, thirty-three in all on top. Below the girdle are sixteen split triangular, or "upper corner on bottom " facets, whose bases join the corresponding ones on top to form the girdle, and eight pentagonal main facets extending from the girdle to the culet, making with the culet, twenty-five facets on the bottom. A diamond cut thus, if it is properly pro-portioned, shows an equal distribution of light and brilliancy at all distances from the eye. The center under the table is as full of light as the edge facets, because the back facets are holding the light which has entered from the front. If the stone were cut too deep or too shallow, part of the light would pass through the back facets and leave a dark center, called a " well " in a deep stone, or a " fish-eye " in a shallow stone.
Diamonds that are too deep to be at their best, are called thick or lumpy stones, and those that are too shallow are termed " spread " stones if they show weakness in the center at some distances only, and fish-eyes if it is everywhere observable. Mr. O. M. Farrand discovered a method of remedying over-spread stones, by elongating the bottom corner facets, carrying the points down 3/4 to 7/8 of the distance from the girdle to the culet.
Some stones are naturally more brilliant than others, but many diamonds would be more brilliant if cut better. As very many crystals are quite irregular in shape, absolutely correct cutting would often entail too much cost. Very many more persons recognize the beauty of a perfectly cut stone when they see it, than the number of those who are willing to pay the extra cost in time and material necessary to secure it. For that reason, though the average cutting to-day is very good, and conforms generally to the proportions of excellence, a large number are not mathematically exact, and when they are so, the price appears to many unreasonably high.
Although a knife-edge girdle requires care in setting the stone, and renders it liable to chip and splinter from contact with others if it is set in an open or clamp setting, it is ideal cutting. Mr. Ernest G. H. Schenck patented a process for forming the stone with a continuous polished curved facet running around it at the girdle, thereby eliminating the unfinished appearance of a rough edge and the liability of a knife-edge to chip. Some cutters cover thickness at the girdle by polishing the edge. As the price of rough went up, many cutters, in order to get as much weight in the finished stone as possible, and therefore more money for it without adding to the price per carat, made the girdle very thick. In that way considerable weight was added without attracting attention, as the extra thickness lay through the body of the stone at its greatest dimension. These were called bicycle-tire stones. This kind of cutting makes a diamond cost less per carat, but the stone costs as much as one of the same size with a fine edge which weighs less and is more brilliant. There was a time, not long ago, when the public commonly demanded a thick or deep stone, because they thought the thicker it was, the better.
Now many go to the other extreme and want them over-spread. The finely cut stone lies between.
Rough diamonds suitable for cutting to gems are of two classes ; " close " goods and " cleavage." The former are shaped naturally for immediate preparation for cutting, as octahedrons. Formerly these were pre-pared by setting two stones in handles and grinding them together, or bruting, until a place was rounded on both where the tables should be, but of late these points are sawed off and utilized. This is done by charging the thin edge of a wheel with diamond dust and cutting through the stone by rapid revolutions, as the facets are cut by pressing the stone against the flat side of a wheel similarly charged. As soon as this practice was established by the cutters, the Diamond Syndicate raised the price of such rough to correspond with the value of the pieces of diamond saved by the process.
The polishing of a diamond is really the grinding of the stone away by contact with the flat surface of a rap-idly revolving horizontal wheel charged with diamond dust and oil. These wheels are hackled or grooved to hold the abrasive and the diamond being polished is pressed down upon it, at different angles for the various facets, until the polishing is consummated.
The " cutting " of a diamond consists in the preparation of the stone for the wheel, and takes the place of the old-fashioned bruting. It is done by setting one rough stone in a turning wheel and another in a stick. The one in the stick is then held against the other revolving in the wheel, and they grind each other down to a girdle, from which the stones are rounded up to a low dome for the table side, and a higher dome for the culet ide. The turning wheel can be thrown off the center so as to take certain parts of the crystal out of the grind in case of dangerous flaws. The process consists really in roughing out the outlines of the stone as it is to be, and cuts to dust about fifteen per cent. of the weight lost in the entire process. Some cutters saw the octahedrons through the center and then cut a shallow bizel side, round off the corners for the pavilion and send it to the wheel for the faceting or polishing. By this method they get over fifty per cent. in cut goods out of the rough material. The temptation is to cut the top side of the girdle too shallow for perfect brilliancy, in order to save weight. This was done. frequently in Antwerp, and those shallow top stones are often called " Antwerp cut."
By new methods now in vogue, the loss of material in cutting has been reduced from sixty per cent. to fifty and in some cases forty per cent., and the work can be done in very much less time. Health conditions have also been greatly improved by the new methods. In the old way, setters were menaced with lead poisoning through the continued handling of lead in the frequent resetting of stones in the dop.
Not very long ago the setting of stones for the wheel was done in a very crude way and consumed much time. The diamond was set in a mixture of lead and tin in a metal cup. A small part of the stone was left exposed and a mark indicating the grain of the stone made on the solder. This method required frequent resetting. During the entire process, the direction of the grain was noted and a mark made for the guidance of the polisher. Each facet had a name by which the grain and how to polish it was known. Since diamond cutting has been done largely in this country, many improvements have been made. A dop, as the holder of diamonds on the cutting wheel is named, is now made, which holds the stone in claws, doing away with the troublesome use of fusible metal, and is so constructed with mechanical de-vices that the whole set of facets can be accurately gauged for the presentation of the stone on the cutting wheel. The wheel makes about 2,000 revolutions per minute and it has been calculated that to polish a diamond weighing l00 carats in the rough, a wheel would revolve over 52,000,000 times.
As Europe did more to advance the art of cutting diamonds in a few centuries than the Orient did in several thousands of years, so the United States has done more in the last decade than Europe did in the centuries. As in other matters, they have taken advantage of the old world's many years' experience to develop the knowledge gained into practical appliances. Precious stones have been long sawed by the Chinese, with a string charged with oil and emery, spun over a bow. It is said that sawing was done on the Regent with lead strips charged with diamond dust, a process possible only where time and labor counted for practically nothing. When the United States took hold of the industry, machines were soon perfected to rip a diamond in any direction at a minimum expense of both time and labor. Today there are numerous patents for sawing, convenient dops, and devices for sawing and splitting the crystal, whereby time, labor and costly material is saved.
Cleavages are crystals of a shape out of proportion to a cut stone. These are split into suitable pieces before going into the cutter's hands. Imperceptible as it is to an inexperienced eye, diamonds have a grain along which they can be split as wood is split, only much more evenly and exactly. This grain is parallel with the faces of the octahedra. Advantage is taken of this to save material and the labor which would otherwise be expended in grinding away superfluous parts, to eliminate interior flaws, and also to improve the color, for by judicious cleaving a number of parts of a crystal may be made to yield a finer color than that of the crystal in its entirety.
To be a good cleaver one must be familiar with rough diamonds and have good judgment; the operation itself is simple. Having studied a crystal and decided just where and how to cleave it, the cleaver takes the edge of another rough diamond fastened in a convenient handle, and grinds it across the edge at the point where the stone is to be split, until there is an incision proportionate to the size of the crystal being operated on. He then uses other " sharps," as the cutting edges are called, until the incision has the appearance of a V-shaped nick. Placing the blunt edge of a flat piece of steel like a short ruler, in the incision, he strikes the other edge a smart blow with a small hammer, and the crystal divides, the two planes of the cleft smooth and shining as glass. After examining the pieces, he places them in the little lock-box always before him, lights a fresh cigarette, and picks up another crystal for examination. About twenty-five per cent. of the diamonds found require cleaving.
Another form of cutting is the " rose cut," used principally for cheap cluster work in countries where the people are not as critical and have less money to spend than those of the United States. Rose cut diamonds are high or low faceted domes over a flat base. They are cut usually from the odds and ends of crystals, small flat crystals, and pieces which cannot be used for brilliants. Most of them are cut in small sizes, though some large ones are cut from flat crystals which will not afford a brilliant. The " Dutch " rose has twenty-four facets in two rows of equal depth. The " Brabant " rose has one deep row below, surmounted by a shallow row. This is cut also with twelve facets or less. The" Rose recoupée " has two rows of high facets, twenty-six in number. The " marquise " and " pendeloque," each have twenty-four facets, and the "double " rose, which is like two ordinary roses joined at their bases, has forty-eight facets. " Briolettes " are pear-shaped or oval stones faceted all over with triangular facets. The " Pendeloque " is a brilliant-cut, pear-shaped stone. The " Rondelle " is a flat, circular stone with faceted edges, usually pierced in the center for stringing between other stones of bead shape ; they are seldom cut in diamond. " India-cut " is a clumsy form of the single brilliant-cut, adopted by East India cutters to preserve weight, and is rarely seen in western markets. " Point-cut " is only found in antique jewels. It is produced by polishing the faces of a regular octahedron.
Great care is not exercised usually in the cutting of roses. Theoretically the facets are even and regularly placed, but usually the stones are simply covered with uneven flat facets to catch the light and glitter. They make very unsatisfactory jewels, for set them as carefully as possible, dirt will collect under the flat backs and produce a dark, unclean effect. Most of them are cut in very small sizes, many as small as several hundred to the carat.
This seems incredible, but a more marvelous fact is that full-cut brilliants with their beautiful arrangement of numerous facets are also cut to such sizes, one hundred to the carat being not uncommon. The thicker roses of twenty-four facets are also called " roses couronees " and the six and twelve facet roses, cut chiefly in Antwerp, are known as " roses d'Anvers."
Single or eight-cut brilliants are used to some extent in the United States in small sizes for cheap work. These are shaped like the brilliant, but have eight side facets on top and eight on the bottom, running from the girdle to the table and from the girdle to the culet. In a paper of melee, the cut is not always observed, and though they are much less sparkling when mounted in clusters than the full-cut, many do not learn it until, after buying the jewel, it comes in comparison with the more expensive jewel made of the full cut brilliant stones.
Of late, in response to a demand for novel effects, many diamonds of the finer qualities have been cut square, marquise, pear-shape and heart-shape. Most of them are cut after the brilliant order of faceting, but some of the square stones are cut with straight parallel facets or " table-cut," similar to the usual cutting of emeralds. These are not used for popular-priced jewels, but are confined to expensive pieces for a class who do not regard cost. Among the novelties in cutting introduced during the last decade, one only attracted wide attention. It was patented by a New York importer and for a time it appeared possible that the form might become permanent. It is known as the " twentieth-century " cut. The diamond is cut round, but the side outline shows a shoulder above the girdle and the pavilion is somewhat bellied. The shape of the facets also differs from those of the brilliant-cut and there are eighty of them. The table is replaced by a low pyramid of facets meeting at a point in the center. It has not proved popular.
A process of grooving diamonds has been patented. Parallel grooves around stones having 8, to, 12, or 18 sides are sometimes cut and regular facets are cut con-cave. Diamonds cut thus have not yet appeared on the market.
In Amsterdam there are 64 factories with an aggregate of 7,000 mills and employing about 9,000 persons. Wages of setters, cutters, and polishers, range from about ten to fourteen dollars per week. Cleavers are paid from fourteen to twenty dollars per week. Ten hours is the working day. Antwerp employs from 4,000 to 5,000, of whom 70 are women. Sorters get six to ten dollars per week and the other workers are paid about the same as those of Amsterdam. In Paris there are a number of cutting shops, but very few of them are for cutting diamonds only. It is so also in London, therefore neither city is regarded as an important center of the cutting industry.
Cutting in the United States was first begun about 1866. Mr. Henry D. Morse of Boston, who soon had a good reputation for fine cutting, operated up to fifteen or twenty mills. A few later followed his lead, mostly as repairers only, however, but about 1881 the old New York diamond importing house, Randel & Baremore, afterwards Randel, Baremore & Billings, opened a cutting shop in connection with their importing business, under the management of John B. Humphrey, the diamond cutter of Boston. Later the shop was in the charge of Mr. Charles H. Bent, who learned the trade with Mr. Morse. They operated about twenty mills. At that time there was but one other shop of the size in New York. Although numerous small shops were opened from time to time, it was not until early in the nineties that any large cutting establishments, operating simply as cutters after the European manner, were started in New York. There are now eight or nine which keep twenty to seventy-five mills going, and there are four to five hundred persons employed in the industry. The polishers earn from $24 to $6o per week. Many of the cutters, saw men and cleavers, work by the piece, some of them, especially the latter, earning very large wages when employed.
By 1897 our imports of rough were considerably over one million dollars per annum. In 1899 they were nearly five millions, and though they fell below four mil-lions the following year, they went to over six and a half millions in 1901 and to about eight and a quarter millions in 1902.
The imports of rough have been as follows:
to June 30, 1873 $176,426
to Dec. 31,
From 1891 to 1896 inclusive, rough in government statistics was either included with all other uncut precious stones, or with unset diamonds and other precious stones.
1897 $ 1,386,726
From 1873 to 1883 inclusive, these figures include glaziers' diamonds and other diamonds, except those for jewels and diamond dust.
From 1884 to 1890 inclusive, they are for rough or uncut diamonds alone.
From 1891 to 1896 inclusive, rough was included with other items so that definite figures cannot be given. From that time the figures stand for rough only.
The amount for 1908 includes all uncut diamonds except bort, which amounted to $180,389.
Import statistics as published from time to time are misleading, as they are sometimes given for the year ending June 3o and at other times for the year ending December 31. The figures also cover at times one or all of the various kinds of uncut diamonds, i. e., miners, glaziers, engravers, bort and dust. In some cases other rough precious stones are also included under the one heading of " diamonds uncut." As nearly as possible the foregoing figures represent the amount in value of rough diamonds imported to be cut to jewels.