The Wonder Book Of Knowledge Part 71

The Story in Diamond-Cutting[71]

Diamonds were known and worn as jewels (in the rough) in India 5,000 years ago and used as cutters and gravers 3,000 years ago. India was the source of supply until diamonds were discovered in Brazil about the year 1700, when Brazil became the largest producer and remained so until diamonds were found in South Africa about 1869. The African mines now produce four-fifths of the diamond supply. Previous to the discoveries in Africa, diamonds were known to originally come only from high places in the mountains, because the diamond deposits were found in India and Brazil, on high plateaus, on the sides of mountains, in the beds of mountain streams, and in the plains below; where mountain torrents had rolled them.

In Africa, for the first time, the true original home of the diamond was found at high levels in the mountains, in enormous fissures, open chasms, chimneys or pipes, extending to great and unknown depths. Into these immense chimneys, nature forced from subterranean sources, slow rivers of a peculiar blue clay, a diamondiferous earth termed "serpentine breccia" or "volcanic tuf" and now known by the latter-day name of "Kimberlite." As this soft mixture oozed into the "chimneys" or "pipes" from the bottom, it was gradually forced upwards, filling the whole chasm from wall to wall and to the top, where its progress ended by hardening in a small mound ten to twelve feet higher than the surrounding surface.

In this blue clay or Kimberlite in these chimneys, is found nature's most wonderful creation, the diamond crystallized from pure carbon, in intense heat, and under t.i.tanic pressure.

The greatest mines of Africa are the Jagersfontein, Wesselton, Premier and Robert Victor. The Kimberlite of the Jagersfontein mine is free from pyrites, and to that is attributed the remarkable brilliancy and purity of color for which the diamonds of this mine are celebrated. Their color includes the blue, and they command the highest prices of any diamonds.

The Wesselton mine crystals are noted for their octahedra and purity.

The color and brilliancy are so superior that nearly all fine white "Rivers" are rated as Wesseltons. The Robert Victor yields a big average of fine white stones, and many of the crystals are very perfect and beautiful. The Dutoitspan diamonds mostly show color, but many are "fancy" and demand a high price. The Bulfontein crystals are usually small white octahedras of very good color, but many are flawed. The De Beers stones are good white, some color, some broken crystals and smoky stones. The Kimberly diamonds are much the same as those from the De Beers mine. The Premier is the largest diamond mine in the world. Of its diamonds some have an oily l.u.s.tre and are quite blue--many are of the finest quality and color. This mine also produces a large number of "false color" stones which change color in different lights. The Voorspoed and the Koffyfontein produce fair white and some colored diamonds.

Diamonds in small quant.i.ties are also found in Borneo, British and Dutch Guiana, Australia, Sumatra, China and the United States.

One of the largest diamonds known (weight 367 carats) was found in Borneo about a century ago, and belongs to the Rajah of Mattan. One of the most celebrated is the Koh-i-noor (Mountain of Light), belonging to the British crown. It weighed originally nearly 800 carats, but by subsequent recuttings has been reduced to 103-3/4 carats. The Orloff diamond, belonging to the Emperor of Russia, weighs 195 carats; the Pitt diamond, among the French crown jewels, 136-1/2. The former, which came from India, has been thought to have originally formed part of the Koh-i-noor stone. The largest Brazilian diamond weighed 254-1/2 carats and was cut to a brilliant of 125. Some of the South African diamonds are also very large, one being found in 1893 weighing 971 carats, or nearly half a pound. More recently a much larger one has been found, weighing 3,034 carats. This has been cut into eleven pieces, the largest, a drop brilliant, weighing 516-1/2 carats. This, called the Star of South Africa, has been placed in King George's scepter, and another, of 309-3/16 carats, in his crown.

A rough diamond is a hard-looking, luminous object, somewhat like a piece of alum, with a dull skin, called the "nyf," over a brilliant body. The ancients wore their diamonds uncut because they could not find a substance that would grind or cut them. About 1,500 years ago, however, it was found that by rubbing or grinding one diamond against another the outer skin could be removed. At Bruges, in 1450, diamonds were first polished with diamond dust. In Holland, in 1700, diamonds were first cut with an idea of bringing out real beauty and brilliance by cutting them square with a large flat table and some small facets, ten in all, sloping to the edge of the square. From this beginning cutters gradually added additional facets to increase the brilliancy until there were thirty-four in all. Then came the English round-cut brilliants with fifty-eight facets, but the diamond was left thick and lumpy, until about seventy-five years ago, when an American cutter, Henry D. Morse, of Boston, developed the cutting of diamonds to its present perfection by fearlessly sacrificing weight to get proportion.

This greatly increased the price of diamonds, but enhanced their brilliancy.

[Ill.u.s.tration: OLD SQUARE CUT DIAMONDS]

[Ill.u.s.tration: ENGLISH SQUARE CUT DIAMONDS]

All cutters have been compelled to follow this method, and the perfectly cut brilliant of today has a depth from table to culet of six-tenths of the diameter, of which one-third is above the girdle and two-thirds below. In this form the diamond resembles two cones united at their bases, the upper one cut off a short distance from its base, the lower one having its extreme point cut off. It has fifty-eight facets, of which thirty-three, including the table, are above the girdle and twenty-five, including the culet, below the girdle. Stones which are not scientifically cut in this true proportion, if too deep, are called "lumpy," if too shallow they are called "fish eyes." A slightly spread stone is desirable, provided it has not lost brilliancy, and so become a "fish eye." Looking larger than its weight indicates, it offers a larger appearing diamond for the price of a smaller perfectly cut stone. Most cutters remove as little of the rough stone as possible in cutting so as to retain weight (they sell by weight). This often results in the finished diamond being too thick at the girdle, making a lumpy stone.

Many people think deep, lumpy stones are most desirable. This is not true, as they are imperfectly cut.

In preparing to cut a diamond the rough crystal is studied until the grain is found. Along the grain another sharp-pointed diamond is ground until there is a V-shape incision or nick. The blunt end of a flat piece of steel is placed in this nick and a smart blow of a hammer divides the crystal evenly and perfectly. After this "cleavage" has removed the unnecessary portions, or they have been sawed off by the use of rapidly-revolving thin wheels charged with diamond dust, the diamond is set in a turning wheel and ground with another diamond until it takes the shape in which we know it.

The fifty-eight facets are cut and polished one at a time on a rapidly-revolving wheel charged with diamond dust and oil. It takes from two and one-half to four days to properly cut a stone. Knife-edge girdle diamonds are impractical owing to the liability of chipping the thin edge in setting or by blows while being worn. Polishing the rough edge of the girdle is rarely done and then usually to conceal a girdle which is too thick or lumpy. The princ.i.p.al diamond cutting centers are Amsterdam, Antwerp and New York.

[Ill.u.s.tration]

Inherent flaws can be perfectly understood by imagining a pond of water frozen solidly to its center. At the sh.o.r.e, where the ice has been partly forced out along the banks, it will be full of gra.s.s, leaves, pebbles and sticks, and presents a broken and frosted appearance.

Further out there are only traces of such debris, some bubbles, spots, etc. Out at the center is clear, transparent, unbroken, unflawed, purest blue-white ice, such as you delight to see in your gla.s.s on a hot day.

So is it with diamonds; some (like the ice along the sh.o.r.e) are full of cracks, carbon specks, bubbles, clouds, splits and cavities; some have all of these; some only a few; others only one, and some are without flaws.

[Ill.u.s.tration]

Of all the imperfections (not considering glaring cracks or nicks), carbon spots are the most discernible. They range from mere specks scarcely visible with a powerful magnifying gla.s.s, to large black spots or cl.u.s.ters of large or small black specks sometimes quite plain to the naked eye. These are carbon which failed to crystallize with the rest of the diamond, or intrusions of t.i.tanic iron. The blackest and often most numerous carbon specks occur in the finest white and blue-white stones.

"Capes" and other yellow diamonds are usually perfect, something in the color of these stones seemingly being of a nature which helps clear and perfect crystallization. Blue-white stones of exceptionally fine color are often ma.s.sed full of s.h.a.ggy or jet-black carbon spots.

White specks and bubbles are common flaws, which vary in size and which may be best ill.u.s.trated by looking at a pane of gla.s.s in your window.

There you will find small knots, white bubbles and whitish specks.

These seldom injure the brilliancy, as they are often a glittering silver color, more brilliant than the diamond.

Clouds are dark flat patches in the grain, of a brownish color, and appear as a sprinkling of dust in a small patch in the interior. This seldom injures brilliancy.

Glessen or gla.s.ses are flat sectional streaks having an icy appearance.

When large or abundant they disturb or cut off the proper reflection of the interior light rays, causing an appearance known as "shivery." When clouds or glessen occur at the surface of a diamond they appear as cracks, and if at or near the girdle are dangerous, as the stone is liable to split or crack there when being mounted or by any hard blow, which would result in the loss of a sliver or wedged-shaped piece out of the edge.

[Ill.u.s.tration]

Surface flaws consist of nicks or cavities in the face of the stone either above or below the girdle. The brilliancy of the diamond hides these flaws when the diamond is clean, but when clouded with soap and dust these cavities fill up and show plainly.

[Ill.u.s.tration]

Diamonds are so brilliant, the radiance from the facets so bewildering to the eye, that the flaws cannot be seen by the human eye unless the imperfection is p.r.o.nounced and at the top surface of the diamond. Each facet of a diamond (by reason of the method of cutting) is a window looking down a clearly defined walled chamber, like a hall-way to the culet. With a one-inch loup or magnifying gla.s.s such as watchmakers and diamond dealers use, it is possible to clearly look down through each facet and its hall-way to the culet, and observe throughout each chamber the very slightest imperfection if one exists, thus thoroughly examining and exploring the entire diamond.

Diamond brilliancy is of two kinds: "surface brilliancy" and "internal brilliancy." Light falling vertically on a diamond is reflected back in straight, unbroken rays. This const.i.tutes "surface brilliancy." Light falling in a slanting direction is partly reflected and partly enters the stone; that part which enters is refracted or bent and causes the "internal brilliancy."

In a perfectly cut diamond, the facets are so carefully arranged that entering rays of light jump from wall to wall of this transparent enclosure and emerge again at the very point of entry. Cleverly arranged mirrors sending a ray of light from one to all the others and back again to the first will produce the same effect. Lights entering a diamond are reflected, refracted and dispersed. The dispersion of a ray of white light separates it into its component color rays. These are the spectrum colors often seen radiating from a diamond. Placing a diamond in the sun's rays and holding a sheet of white paper at the proper angle to catch the reflections from the stone clearly shows these colors.

[Ill.u.s.tration: MODERN AMERICAN CUT DIAMONDS]

Brilliancy is often said to be the most important quality of a diamond, but that is not true. Yellow diamonds are more flashingly brilliant than white stones that cost much more. In each color grade, greater brilliance determines higher value over stones of the same color grade with less brilliancy. The diamond is the hardest known substance in the world, cutting and grinding all other known hard things, but itself only cut and ground by its mates.

Because of their hardness, diamonds worn by many previous generations remain as brilliant as they were in the beginning and they will continue so to the end of time.

No other thing can scratch or mar the polished facets and sharp corners of the diamond. It is the hardest of all known things. While all diamonds are of practically the same hardness, this is not, however, absolutely true, as stones from wet diggings or rivers are slightly harder than those from dry diggings. All diamonds are infusible and unaffected by acids or alkali. The heat of a burning building will not affect them, they can be raked from the ashes uninjured and can only be burned in oxygen under a scientifically produced intense heat of 4000 F. While the hardest known thing, the diamond is brittle and can be crushed to a powder. It is the only absolutely pure gem, being composed of crystallized carbon--all others are composed of two or more elements.

The term "Shibboleth" has come to mean a countersign or pa.s.sword of a secret society since the Biblical days, when the Ephraimites, who had been routed by Jephthah, tried to pa.s.s the Jordan. They were made to p.r.o.nounce the word "Shibboleth" and were easily detected as enemies when they p.r.o.nounced it "Sibboleth."

Why do We Get Hungry?

Hunger is a sensation partly arising in the stomach, since it may be relieved temporarily by the introduction into the stomach of material which is incapable of yielding any nutriment to the body. It may be due to a condition of fulness of the vessels of the stomach, relieved by any stimulus which, acting on the lining membrane, induces a flow of fluid from the glands. But it also arises from a condition of the system, since the introduction of nutriment into the blood, apart altogether from the stomach, will relieve it. This is also evident from the fact that hunger may be experienced even when the stomach is full of food, and when food is supplied in abundance, if some disease prevents the absorption of the nourishment, or quickly drains it from the blood.

Hunger may be partially allayed by sleep or by the use of narcotics, tobacco and alcohol, all of which tend to diminish the disintegration of tissues.

The Story in the Modern Lifting Magnet[72]

Nearly every boy has had among his treasured possessions a small horseshoe magnet, painted red, with bright ends, and has spent many happy hours picking up needles, steel pins or other small objects, and finally tired of it because of its small lifting capacity and dreamed of one which would lift a hammer, or possibly even the family flatiron.

Little did he know at that time of the long and interesting history of magnetism, the many stories and superst.i.tions based on its strange power; or of its intimate relation to the wonderful growth of electricity within the last hundred years. His wildest dreams of lifting power would be realized if he could see a modern electric lifting magnet which has only come into use within the last ten years and is meeting with instant approval in nearly every industry where iron and steel is handled in any quant.i.ty.

[Ill.u.s.tration: FIG. 1]

There are three primary kinds of magnets: the lodestone or natural magnets, the artificial or permanent steel magnet, and the electric magnet. At present the lodestone is little used. The permanent steel magnet is used for compa.s.s needles, as the familiar horseshoe magnet, and in certain types of electric machinery. The electric magnet forms a part of nearly every kind of electrical machinery and is by far the most useful form of the magnet. The modern high-duty lifting magnet is a form of the electric magnet.

The properties of the lodestone and the permanent magnet have been known for thousands of years, while the electric magnet is a comparatively recent discovery.