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and specific gravity of the principal precious perty and the brilliancy of diamonds under stones:
artificial light, particularly candle light, which brings out most clearly the quality of first-class stones. The most sparkling stones show a notable fluorescence of a very luminous and
clear blue. In a jewel-case in which Diamond 10 3'5
grouped diamonds of all qualities, the gems Ruby 40
when illuminated by violet light, assume diffeSapphire 9
rent tints from a vivid blue to sombre violet. Chrysoberyl 3*7 Topaz 8 3.5
As soon as the light removed all derees of Spinel 8
phosphorescence are noticeable, the jewel-case I.merald 73 27
appearing to be studded with glow-worms, Zircon 7346 Garuet
some very bright, others almost extinct; the 7 Cordierite 7
most sparkling stone will be found to be the Tourmaline in 131
best. Quartz 7
2'6 Chalcedony of
The origin of the diamond has long been a 31 Opal 6 2'3
matter of discussion. It seems probable that Turquoise 6
diamonds have been formed by crystallisation Nephrite 6 3'0
from molten rock masses. Minute crystals of Lapis-lazuli 51 24 Malachite.. 38 39
diamond have been found with graphite in Amber 11
slowly-cooled steel, and in meteorites. Mr.
E. F. Heneage has arrived at the Diamond.---The diamond is the hardest clusion that the diamonds of South Africa substance known. It is, however, very brittle. were formed at a very great depth in the Chemically it is pure carbon; it is combustible, various pipes from accumulations of infusible, and unassailable by acids. In the bonic acid. The difficulty of reproducing rough form it is devoid of brilliancy and is only these conditions of great heat and pressure semi-transparent. It is usually cut in one of artificially has been overcome by Professor the three forms, termed the brilliant, rose, and Moissan, who found that iron, at a high table, the first being the best for developing all temperature and under great pressure, will its beauty. The double - cut brilliant was act as a solvent for carbon, and will allow it formerly square with a high crown, but with to crystallise out in the form of diamond. The the advent of the South African stones and diamond is usually found as loose crystals in the American cutter the brilliants were cut alluvial deposits. The most important of these round with a rather flat crown. Recently deposits are those of India and Brazil. The in America modification of the
former deposits were known in very early times, brilliant forms of cutting with twenty facets, and Golconda was the centre of the diamond has been patented under the name of 20th trade of the antique world. At the present century cutting. Besides their use in jewel- time the diamond production of India is insiglery and glass - cutting, diamonds have nificant. The Brazilian diamonds were disnumerous industrial applications. They are covered in 1728. The provinces of Minas used for jewelling watches, 100 or 200 of Geraes and Bahia are the most productive. them, when prepared for this purpose, weigh- The diamonds are found in alluvial deposits ing only one carat (3,1 grains or 2055 milli- derived from the materials brought down from grammes). Diamond powder is used for drill- the hills bordering the higher parts of the ing and polishing. Mounted diamond points valleys. It is estimated that since the openare used for engraving, and the black variety ing of the Brazilian mines they have yielded is used for the cutting of millstones, and in the altogether three tons of diamonds. The output crown of rotatory rock drills. Recent re
in 1902 was 40,000 carats. In Borneo diamonds searches have shown that the ray's emitted by are found with gold. The production in 1901 radio-active' bodies induce fluorescence in was 1,972 carats. Since the introduction of diamonds. In this way, diamonds can be dis- the South African supplies the production has tinguished from other precious stones. Years fallen. The famous Borneo diamond, of 367 ago, the fluorescence of diamonds under the carats, known as the Matan,” from the influence of various coloured rays was noted, territorial title of the Rajah to whom it belongs, and Chaumet has ascertained that there is a has been thought to be the largest known, and close relationship between this fluorescent pro- was estimated to be worth $269,378. The
Dutch made very large offers of money and the blue ground being then thought to be bedwarlike material for it early in the 19th century, rock. In 1887, Mr. Gardner F. Williams but they were always resused. The stone, it introduced a system of mining in which all the appears, was examined in 1868, and proved blue ground is removed by overhand stoping to be only a rock crystal with a specific gravity from the rock wall farthest from the shaft, the of 2.63, thus confirming doubts previously broken surrounding rock being allowed to run expressed as to its being really a diamond. in and fill up the stopes. The levels are 40 About 95 per cent. of the world's supply of feet apart, with main levels, from which hoist. diamonds is produced in South Africa. The ing takes place, 320 feet apart. The main diamond mines of the Kimberley field have shaft at Kimberley is 2,160 feet deep. been described in papers read before the Society The winning of the diamonds is an interestby Professor J. Tennant* in 1870, and by Mr. ing process. The blue ground, deposited from R. W'. Murrayť in 1880 ; and in 1893 I read a trucks conveyed by endless chain haulage, is papers describing a visit to the mines. Since 'harrowed as it lies exposed to the disintegratthen many changes have have taken place, ing action of the sun and rain, on the depositand a brief account of the development of the ing floors. These have a hard and level surindustry may not be out of place. The story face, and at De Beers cover an area of about of the accidental discovery of the diamond
two square miles. The blue ground, spread to fields in 1867 has often been told. The first a thickness of nine inches, lies exposed for diggings were river washings, for the existence
about six months before it is thoroughly disir.of diamonds away from the Vaal was not sus- | tegrated. Even at the end of that time, there pected, until, in 1870, garnets were discovered is some 14 per cent. of the material that is not on a Boer farm, and diamonds were looked for. acted on, being so hard that it has to be This caused the great rush to Kimberley. The crushed. When the disintegration is commines were worked as deep, open quarries, the plete, the material is hauled to the washing diggers working independertly, and a system machines, where it is raised by a lift, and of aerial ropeways was developed, that made
passed through a revolving cylindrical screen the mines look like a spider's web. In 1879, with 1 inch holes. The lumps pass out for continued falls of rock from the sides of the
further treatment, whilst the pulverised blue excavations, and the constant influx of water,
ground passes into shallow annular pans in led to the idea of sinking shafts at the side of which are mounted revolving toothed arms. the quarry, and of reaching the diamond ground The diamonds and heavier matter pass to the by underground galleries. As time went on, outside, whilst the lighter waste material flowexcessive competition reduced the price of ing towards the centre, is discharged. The diamonds to the lowest ebb, and Cecil Rhodes entire
is driven by electric motors. and others associated with him conceived the The concentrates are conveyed in locked idea of amalgamating the various companies. trucks to the pulsators which are similar to The amalgamation was skilfully accomplished, the jigging machines used in ore-dressing. and the De Beers Consolidated Mines, Ltd.,
The heavy material obtained, containing the acquired control of the diamond trade of the
diamonds was, until recently, taken to the world, the cheque finally paid in 1889 for the
sorting tables, the sorting being conducted shares in the Kimberley Central Company being first when wet by skilled workmen, and again the largest drawn up to that date. The five
when dry by native convicts. This tedious mines at Kimberley, the De Beers, Kimberley, procedure was done away with by Mr. Kirsten, Du Toitspan, Bultfontein, and Wesselton, occur who invented the automatic diamond sorter in a circle four and a-half miles in diameter. termed the “ greaser,” in which a table The deposits are evidently the result of the
built up of five steps covered with a coating filling-in of extinct craters with volcanic mud of thick grease is vibrated rapidly as the from below. The matrix of the diamond, the concentrates are allowed to drop on to the blue ground, is a breccia composed of shale,
top step gradually. The diamonds adhere, basalt, and diorite cemented together by whilst the garnets, zircons, mica, magnetite, olivine rock. The weathered upper portion of pyrites, and other minerals are washed off. the blue ground is known as yellow ground; The diamonds are boiled in caustic soda to and this is what was worked in the early days, clean them. Formerly, out of 192,000 cubic
feet of blue ground washed daily at De Beers • Journal of the Society of Arts, vol. 19, p. 15. • Ibid, vol. 29, p. 370.
and Kimberley mines, 160 cubic feet had to i lbid, vol. 41, p. 168,
be sorted by hand. Now, with the appli.
the period of the agreement with the company. These compounds, of which there are twelve, consist of rows of iron buildings placed along the sides of a large square, which is surrounded by a 10 foot wall. The largest one at the De Beers mine covers an area of about five acres, and affords accommodation for 2,000 natives. The houses which the natives occupy are clean, lofty, airy tenements, with sleeping bunks arranged somewhat as in large steamers. Sanitary regulations are strictly enforced; and an
pipes and cigars, and an abundance of fresh meat. The Kaffirs buy their own provisions and do their own cooking, members of the same tribe frequently clubbing together for this purpose. The compound is also provided with a hospital, dispensary, church, and school.
Next in importance to the four great mines of the De Beers Company, to which reference has been made, is the mine at Wesselton, which was not discovered until 1890. It is worked as an open quarry, and yields clear stones of irregular shape. The extent of the operations of per load.
the De Beers Company is clearly shown in the the Transvaal, some 25 miles to the east of statistics of production for the year ending | Pretoria. The production of these deposits in June 30th, 1902, the output of diamonds having the year 1902-3 was 33,572 carats, valued at been 2,025,224 carats from blue ground, 202,830 £46,358. In August, 1903, alone, at the three carats from tailings, and 18,728 carats from mines in the Pretoria district, 14,230 loads old concentrates. At De Beers and Kimberley, were washed, yielding 16,135 carats, valued at 2,062,459 loads of blue ground were hoisted, £21,676, the average yield being 1.134 carat yielding 1,491,012 carats of diamond valued
The following are the principal at £3,465,050. The number of carats yielded mining companies in which British capital is per load was 0.76, the value per carat being invested:
Name of Company.
Situation of mines.
Minas Geraes. Kimberley, leased to De Beers.
Barkly West, Cape Colony.
Brazilian Diamond Field Corporation, Ltd..
60,000 Consolidated Bultfontein Mine, Ltd.
721,500 Diamond Exploration and Finance Syodicate, Ltd. 22,500 Elandsdrift Diamond Estates.
300,000 Frank Smith Diamond...
250,000 Griqualand West Diamond Mining Co., Ltd. 1,057,000 Inverell Diamond Fields, Ltd.
381,307 Kamfersdam Mines, Ltd.
300,060 Koffyfontein Mines, Ltd.
220,427 Lace Diamond Mining Co., Ltd.
250,000 Malacca Diamond Mines, Lid.
550,000 Otto's Kopje Diamond Mines, Ltd.
1902 1902 1888 1902 1901 1900 1881 1900 1896 1893 1899 1900 1887 1902
Kimberley, leased to De Beers.
The cost of production per load was 85. 53d. The Premier mine at Wesselton produced 1,932,140 loads yielding 561,990 carats valued at £941,300.
The number of carats per load was 0-30, the value per carat being 33s. 6d. The cost of production per load was 3s. 5d.
In the early days, a good deal of the waste from the mines was used for making up the streets of Kimberley, and, at the present time, the streets are being washed for diamonds, with very remunerative results. Outside Kimberley there are several diamond mines, but none have attained the success of the Kimberley mines. At Jagersfontein, where diamonds were discovered in 1870, the stones are of better quality than De Beers, but the average yield is much less. On the Vaal river, where river washings were extensively carried on; the deposit is similar in composition to that of Kimberley, and is worked as a quarry by two companies. The mineral is screened, and washed and treated on greasers, as at De Beers. The stones are small but of good colour. The most recent development of the South African diamond industry, has been the wonderful discoveries of diamond deposits in
The existence of diamonds and other gems in New South Wales was recorded as early as 1851, but no systematic attempts to work the deposits were made until 1872, and little success attended the industry until 1890. The diamonds occur in the Inverell and other districts in old Tertiary river drifts. The diamonds are harder and whiter than the South African ones. The majority of diamonds obtained weigh from 1-6th to 1-5th carat, while the largest vary from 2 to 3 carats. The number obtained per load varies very greatly; the Round Mountain Company at Cope's Creek, in the Inverell district, washed 722 loads for 2,685 carats in 1886, obtaining from six loads the exceptional yield of 1,080 diamonds, weighing 296 carats. In 1902, the Inverell Diamond Fields, Ltd., obtained 4,538 carats from 4,640 loads. The total output of New South Wales was 11,995 carats, valued at £1,1326, and the Malacca Diamond Mines, Ltd. (Fig. 13)
now giving regular returns of 1} carats of diamonds to the load. Another source of diamond supply is British Guiana, where, in 1901 there were produced 91,286 diamonds, weighing 8,227 carats,
Although known in ancient times, diamonds were for centuries but little used as ornaments. The practice of roughly cutting diamonds is of great antiquity, but it was not until 1456 that Louis van Berghem, of Bruges, discovered the art of cutting into facets. The double-cut brilliant, now the usual form, was introduced, by Vincenti Peruggi, of Venice, at the end of the 17th century. The centre of the diamondcutting industry is Amsterdam, where some 12,000 workmen are employed. Of late years Amsterdam has lost the monopoly it formerly possessed, and more diamonds are cut in New York, London, and Antwerp. The finest stones are those from India. The oldest known and largest, the Great Mogul, was seen by Tavernier in Delhi, in 1665. It was subsequently lost. Its weight was 280 carats, and the uncut stone must have weighed 787 carats. The Orloff diamond (193 carats), mounted in the Russian Imperial sceptre, and the Kohinoor (originally 186,4 carats) also of Indian origin, and similar in form. The latter was recut in 1852 with a duction in weight to 106,5 carats. The most beautiful cut brilliant is the Regent or Pitt diamond in the possession of the French Government, which was recut in London in 1717, and thereby reduced in weight from 410 carats to 1363. The Florentine diamond now in the possession of the Emperor of Austria is 133} carats in weight and cut in the usual manner. The Nassak diamond, 893 carats, is of an irregular triangular shape. The Pasha of Egypt diamond weighs 40 carats. Every year we hear of new discoveries in South Africa of diamonds of remarkable size. The largest, the Excelsior, was found in 1893 at Jagersfontein, and weighed 971 carats. The yellowish De Beers diamond, 428} carats, gave when cut a brilliant of 288} carats. Of coloured diamonds, the Hope blue diamond (44) carats) and the pale green diamond (40 carats) at Dresden are the most celebrated. The quantity of diamonds the world has produced up to the end of 1901 may be estimated as follows:
Corundum Gems. India is specially rich in corundum. A large number of localities at which it occurs are mentioned in Mr. T. H. Holland's monograph published by the Geological Survey of India. There are large deposits of the common form of this mineral, emery; and the most highly prized specimens of its transparent red variety, the ruby, have been obtained from Burma, whilst the mines of Kashmir are noted for the size and transparency of the blue variety, the sapphire. Until recently nearly all the known occurrences of corundum were in detrital material. Mr. C. Barrington Brown was the first to prove the existence of the ruby in situ in crystalline limestone, and in conjunction with Professor Judd he has published a masterly memoir on the subject in the “ Philo. sophical Transactions of the Royal Society." The most important locality is near Mogok, in Upper Burma. The rubies occur in a clayey mass, an alteration product of a coarsely granular marble. Sapphire, spinel, and tourmaline are also met with. This marble appears to have been derived by contact metamorphism from a dolomite limestone of Upper Carboniferous age. Such limestone still stands unaltered in many places, and in others has been altered into marble by up-bursts of eruptive rock. The clay containing the rubies lies at the side of valleys and fills wide cavities. The stones found are much worn and corroded on the surface. The Burma Ruby Mines Co., Ltd., founded in 1889 with a capital of £150,000, is now, after many difficulties, obtaining very satisfactory results. In the year ending February 28th, 1902, a dividend of 17) per cent. was paid. During the year 1901 the Company washed 947,444 loads of gem earth at a cost of 10:29d. per load. The production included 210,784 carats of rubies, 9,786 carats of sapphires, and 10,241 carats of spinel. The methods of mining for the ruby in Burma are suited to the three modes of its occurrence in the limestone, in hill detrital material, and in the alluvial deposits in the valleys. In the quarries blasting is unsuitable as it injures the gem stones. The dirt is raised by endless ropes from quarries 50 feet deep. Stones of greater weight than four carats are of such exceptional occurrence that they command fancy prices. The largest known were brought from Burma in 1875 and weighed 37 and 47 carats respectively. They are said to have been sold for £10,000 and £20,000. English cut sapphires under one
20,000 New South Wales
110,000 Borneo and India....
15,000,000 South Africa
or about 17 tons.