DIAMOND. This gem, the most highly valued and brilliant of precious stones, is also remarkable for its history and its peculiar physical and chemical properties. Though not always accurately distinguished from other similar stones, it seems to have attracted notice at a very early period, especially in India, the chief source of supply in ancient times. The old Jewish doctors regarded the jahalom, the third in the second row of stones in the breast-plate of the high priest (Exod. xxxix. 11), as the diamond, and it is thus translated in the English and other versions. But as each stone bore the name of one of the tribes, and there is no reason to believe that any method of polishing such hard stones, still less of engraving letters on them, was then known, the identification cannot be accurate. Among the Greeks it is first mentioned about three centuries b.c. under the name of adamas (dδ<i∕xαs), “the unsubduable,” referring to its hardness and power of resisting fire. The same name was previously given to a metal highly valued from its extreme hardness for armour and weapons, and the twofold.use of the term continued long both in Greek and Latin. The name of the gem in our own and most modern languages is derived from this old name, occurring in the form diamas in Albertus Magnus and other authors of the 13 th century. Curiously enough, the French aimant, applied to the magnet, comes from the same term in its other signification of an ore or metal.
The fullest account of the adamas as a stone is found in Pliny, who says it exceeds in value all human things, and its use was confined to kings, and to few even of them. He mentions six varieties, the most remarkable being the Indian and Arabian, of such unspeakable hardness that when struck with a hammer even the iron and anvil were torn asunder—“ita respuentes ictum, ut ferrum utrinque dissultet, incudesque etiam ipsi dissiliant.” It also resisted the fire, and could only be subdued and broken down when dipped in fresh warm goat’s blood. Similar fables continued to prevail during the Middle Ages, and even yet have hardly vanished from popular belief. As an ornamental stone it was highly esteemed during the early times of the Roman empire, as some scandalous stories recorded by Juvenal testify, though only stones with naturally polished faces could be used. This fact is proved not only by the words of Seneca—“nec secari adamas aut caedi vel deteri potest”—and others, but f¢om specimens of diamonds set in gold, with no artificial polishing, which have come down both from classic times and from the Middle Ages. This unworkable character long greatly limited both its use and its value; and the more highly coloured rubies, and even emeralds and sapphires, were often preferred to it. It was only after Ludwig van Berquen (or Berghem, as he is often named) in 1476 discovered the mode of cutting and polishing it, that the diamond slowly regained the, first place among gems. Even in the 16th century (1550), Benvenuto Cellini (Trattato dell y orificerio, cap. i.) assigns it only the third rank in value, estimating a perfect ruby of one carat weight as worth 800 scudi d’oro (each equal to about 4s.), a similar emerald at 400, an equal diamond at 100, and a sapphire at 10 scudi. In the same century the use of the diamond for cutting glass and engraving gems seems also to have become known.
The diamond always occurs in crystals of the tesseral or cubical system. Its most frequent forms are the octahedron, or double four-sided pyramid (fig. 1), the rhombic dodecahedron with twelve faces (fig. 2), and others with twenty-four (fig. 3), and forty-eight faces
(fig. 4). The first form is most common in stones from India, the second in those from Brazil. Cubes also occur, but are rare, whilst the icositetrahedron has not been observed. Hitherto the diamond has been described as hemihedric, but Sadebeck from his own and G. Rose’s researches shows it to be holohedric (in the Berlin Monatsberichte, Oct. 1876). The faces are often curved, strongly striated, or marked by stair-like inequalities, hiding the true form. Many of the crystals also are round almost like spheres (fig. 5), or the smaller ones like grains of sand. This does not arise, however, from attrition during transport by water, but is the original shape of the stones. Macles, or twin-crystals, specially of two octahedrons, are common, and the striae due to this structure appear even on the polished facets. The diamond has a perfect cleavage parallel to the faces of the octahedron, and breaks readily both in this and other directions. Contrary to the old and still common opinion, it is rather brittle, and is easily injured by a slight blow or fall. Its hardness—10 in the mineralogical scale—far surpasses that of all other known stones, and was used even by the ancients to discriminate it from other gems. In specific gravity, 3’52 (or 3’515 to 3’525), it is considerably higher than rock crystal, but nearly the same as the topaz, which may thus be mistaken for it. According to Fizeau, it has its greatest density at - 42° ’ 3 C., and below this begins to expand, a property seen in very few other solid bodies. Its expansion by heat is very small, the volume from the freezing to the boiling point of water only rising from 1 0 to 1’00000354. By friction it becomes positive electric. The so-called compact diamond or carbonado of the stone polishers, found as round grains or masses of one or two pounds weight in the washings near Bahia, of a brownish black colour and sp. g. = 3 ’ 012 to 3 ’ 416, is porous diamond mixed with a small amount of other matter.
The optical properties of the diamond are also very remarkable. The purest stones, or those of the first water are highly transparent and colourless. But more generally it is less transparent, and shows various tints, specially white, grey, or brown; more rarely blue, red, yellow, green; and very seldom black. Such stones, when the colours are pure, are often highly valued. It is also distinguished by its brilliant adamantine lustre. Newton, two centuries ago, remaιked its high refractive power, and from this conjectured that it was a substance of a peculiar nature. The index of refraction is 2’4135 for the red rays, 2’4195 for the yellow, and 2’4278 for the green. This high refractive power, and the strong reflection at both surfaces, render it seldom completely transparent, but give it the high lustre for which it is valued as an ornament. They also produce the numerous internal reflections seen in the interior of cut stones, all the rays of light falling on the posterior surfaces at angles above 25° being totally reflected. Like all crystals of the same system it possesses only simple refraction, but Dr (Sir David) Brewster found that many showed traces of double refraction by their action on polarized light. This he ascribed to a peculiar tension produced in the interior of the stone during its formation, and a somewhat similar explanation is still adopted.
In a history of gems published early in the 17th century, Boetius de Boot conjectured that the diamond was an inflammable body. Robert Boyle, who in 1664 described its property of shining in the dark, or phosphorescing after being exposed to the light of the sun, a few years later observed that a part of it was dissipated in acrid vapours when subjected to a high temperature. This combustibility of the diamond was confirmed in 1694 and 1695 by experiments with a powerful burning glass or lens made in the presence of Cosmo III., grand duke of Tuscany, by the Florentine Academicians. The experiment of the combustibility of the diamond when freely exposed in a strong heat has been often repeated, and its true character was proved by Lavoisier, who determined that the product was carbonic acid gas. Sir George Mackenzie converted iron into steel by powdered diamonds; whilst Mr Smithson Tennant showed that the carbonic acid produced corresponded to the oxygen consumed. No doubt, therefore, now remains that the diamond is only pure carbon in the crystallized condition, and like it insoluble in acids.
In regard to the action of heat on the diamond, various experiments have been made. Before the blowpipe it is infusible, and closely packed in powdered charcoal it can resist a very high temperature. But when oxygen is present it burns slowly at a temperature usually given at about that of melting silver. Gustaf Rose lately found that when air is excluded diamonds exposed to a temperature at which pig-iron melts, or to the strongest heat produced in the porcelain kiln, undergo no change; but at a higher temperature, like that at which bar-iron melts, they begin, whilst retaining their form, to be converted into graphite. He further observed that when diamonds and graphite were exposed together in the same muffle, foliated graphite'was far more difficult to burn than the diamond, but compact graphite was consumed more readily. In the current of air the diamond gradually became smaller and smaller, but retaining its brilliancy till it finally vanished.
The faces also during burning became marked with peculiar triangular hollows, with their sides parallel to the edges of the octahedron. Seen in a strong light they appear as faces of an icositetrahedron, whilst other regular triangular impressions on the faces of natural crystals of diamond are produced by faces of the dodecahedron. (Rose, “Ueber das Ver halten des Diamants,” &c., in Berlin Monatsberichte, June 1872).
India is the oldest, and was long the most celebrated, or rather the only, source of diamonds. They have been obtained from a wide district on the eastern side of the Deccan, extending from the Pennar river in 14° N. lat. to near the Sone, in Bundelkund, in 25° N. lat. In the south the chief mines were at Cuddapah, Karnul, and Ellore, near the Kishna, in Madras presidency. In this district some of the largest Indian diamonds were obtained, Golconda, however, not being a mine, but a fortress where the diamonds were collected. There were other mines near Nagpore, and east at Sambhalpur, on the Mahanuddy, and north at Panna, in Bundelkund. At all of these the diamond was sought chiefly in recent deposits, beds of sand and clay, or in some places a ferruginous sandstone or conglomerate, but probably none of them the original matrix. Heyne states that the diamond has hitherto been found only in alluvial soil, or in the most recent rocks; and that the stones are not scattered through the whole of these beds, but confined to one rather harder than the rest. The upper stratum, of 18 inches, consists of sand, gravel, and loam; next there is a deposit of stiff black clay or mud, about 4 feet thick; and next the diamond bed, which is distinguished by a mixture of large rounded stones. It is from 2 to 2∣ feet thick, closely cemented together with clay. Sometimes this stratum is covered with calcareous tufa. Here shallow pits are excavated, of a few feet in diameter, in such spots as the practice of the workman may induce him to select; he sinks to a depth of a few feet, and searches the bed which he considers most promising for his purposes; and if he meets with little encouragement, he shifts his situation and proceeds elsewhere. Thus a great deal of the country may be turned to waste and neglected. The working was chiefly in the hands of certain tribes or castes, but was conducted on no regular plan, and afforded a very miserable livelihood. There has been little change since, and though mines still exist at Panna, Karnul, and a few other places, but comparatively few diamonds are found, and probably scarcely pay the expense of collecting them. Diamonds have also been long collected in Borneo, at Pontiana, near the southeast extremity of the island. They occur in a red clay along with gold and platina, and the rajah of Mattan is said to possess one weighing 367 carats, of the purest water, but uncut.
During the end of last and the beginning of the present century the supply of-diamonds chiefly came from Brazil. They were first recognized in 1727 in the province of Minas Geraes, where they had been long used by the negroes as counters in playing cards. The principal mines are still in that province near Diamantina (formerly Tejuco), and near Diamantino in Matto Grosso. Mines have also been recently worked in the province of Bahia Other localities are enumerated in the article Brazil. The diamonds are chiefly obtained from the Cascalho, a loose, gravelly deposit mixed with red clay, and containing large lumps of quartz and grains of gold. This rock is probably derived from the itacolumite, a quartzose variety of mica slate, or metamorphosed sandstone, on which it often rests, and in which diamonds are also said to occur. When first brought to Europe the Brazil diamonds were regarded as inferior to those from India, but without reason. Though the mines are strictly watched as Crown property, the produce is nut well ascertained. Martius estimated that in the forty-six years from 1772 to 1818 diamonds weighing about 3,000,000 carats, and worth £7,000,000, were exported. Mr Mawe stated the produce at 25,000 to 30,000 carats annually of rough diamonds, equal to 8000 or 9000 carats when reduced to brilliants. After his time it seems to have greatly decreased, the whole value from 1861 to 1867 being given at about £1,900,000; and the discovery of the Cape diamonds has further reduced the amount. The stones are mostly small, averaging little more than one carat, and very rarely exceeding twenty carats. The largest diamond from Brazil was long an uncut octahedron of 120 carats, but in 1854 a fine stone of 254¾ carats was sent to London. It was an irregular dodecahedron, but of brilliant lustre and with no flaws. Since cut it weighs about 124 carats, and is known as the “Star of the South.”
Diamonds occur in other parts of America, having been found in the Sierra Madre, south-west of Acapulco in Mexico; and a few also in Georgia and North Carolina. They have also been obtained in California, but all small (under 2 carats); and in the district of Arizona, where one is mentioned of 3 carats.
In 1829 diamonds were discovered on the European side of the Ural mountains in the gold washings near the iron mines of Bissersk. Engelhardt conjectured that they were derived from a dolomite rock, but others state that it is mica slate like that of Brazil. Only about seventy were found in the first twenty years, and all of them small, the largest weighing under 8 carats. The only other European locality is at Dlaschkowitz, in Bohemia, where a single diamond was found in the sand containing pyropes,—the one said by Murray to have been picked up in a brook in Ireland being very doubtful.
Not more important are those from Australia, where they were found as early as 1852, and again in 1859, on the Macquarie river. In 1869 they were discovered in the Mudgee, near one of the tributaries of the Macquarie, by gold-diggers, and worked for a time pretty extensively. They lie there in old river drift covered by basalt said to be of Pliocene age. They occur in a similar position in the Bíngera diamond field. In both places they are sparingly distributed and small, the largest mentioned being under 6 carats.
Far more important are the diamond fields of South Africa. In 1867 a Dutch farmer obtained from a boer a bright stone which his children were using as a plaything. This stone was sent to the Cape, where its true nature as a diamond was recognized, and subsequently forwarded to the Paris exhibition and sold for £500. This valuable discovery soon led to further researches, and diamonds were obtained from various places near the Orange and Vaal rivers in Griqua Land West. They were first collected by washing recent alluvial or supposed lacustrine deposits, apparently the detritus of rocks in the vicinity, that are spread over the lower river valleys, but are now rather sought for in “pans,” or “pipes,” of a circular form running down into the inferior strata, or shale, and filled with a peculiar igneous rock, named diabase, or gabbro, often much changed near the surface. Throughout this rock l which has been penetrated to a depth of from 100 to 200 feet, diamonds are disseminated weighing from over 150 carats down to the 100th of a carat, or less. Many are entire, well-formed crystals, but a large proportion are broken and isolated fragments. Hence it has been inferred that the rock in which they now occur is not the matrix or mother rock in which they were originally formed, but that the “pipes” are rather channels by which volcanic matter has made its way to the surface, bringing the diamonds along with it from some inferior deposit. However this may be, diamond-digging has become a regular branch of industry to a large population; and it is probable, though no very accurate estimate can be formed, that nearly fifteen million pounds sterling worth of diamonds have been obtained from this district since their discovery. The largest diamond from the Cape we have seen mentioned is the Stewart, of 288∣ carats, found on the Vaal river in 1872. It was an irregular octahedron of the purest water, and l¾ inch in diameter, and is of a light yellow since cut.
There has been much speculation regarding the mode of origin of these gems, but hitherto leading to no certain result. Newton conjectured that the diamond was “an unctuous substance coagulated;” Jameson thought it might be a secretion from some ancient tree, like amber; and Brewster also traced it to a vegetable source. Lavoisier, Guyton-Morveau, and others observed black specks when diamonds were burned, which were considered as uncrystallized carbon. Petzhold, in 1842, also supported this view, affirming that he had found vegetable cells in the ashes of diamonds. Goeppert, in his Haarlem Prize Essay, in 1863, supported the same view, both from supposed plant tissues and from other inclosures in diamonds, but admitted that the evidence was not free from doubts. Liebig and others have explained its origin by a slow process of decomposition in a fluid rich in carbon and hydrogen. On the other hand, the occurrence of the diamond in the itacolumite or mica slate, and more recently in or near igneous rocks, as at the Cape, has tended to favour the view that it owes its origin to heat or metamorphic action, as is the case with graphite. But this, as graph , 'te also shows, does not preclude the idea that originally it may have been, like amber, some peculiar vegetable product, subsequently altered and crystallized. It may here also be mentioned that all attempts to produce diamonds artificially have hitherto failed.
Diamonds are chiefly used and valued as ornamental stones, and for this purpose they are cut in various forms according to the original shape of the crystals. It is probable that the Indians knew some method of doing this at an early period, and it is said there were diamond-polishers in Nuremberg even in 1373. Berghem of Bruges has the credit of having first used, in 1456, their own powder for this purpose. He found that by rubbing two diamonds on each other their surfaces were polished and facets formed, and acting on this hint, he employed diamond powder and a polishing wheel. His countrymen continued to follow out the art with great success, but some two centuries ago the English cutters were the more celebrated. The trade then reverted to Holland, but is again returning to Britain, where many of the finest stones are cut·. The method has undergone little change, and is still chiefly effected by the hand, partly by rubbing one stone on another, partly by a wheel and diamond powder. Where there are flaws or large pieces of value to be removed, they are occasionally cut by iron wires armed with the powder, or split by a blow of a hammer and chisel in the direction of the natural cleavage. The latter is, however, a dangerous process, as the diamond is very brittle, and many valuable gems have been thus destroyed. When reduced to a proper form, the facets are polished on a lapidary’s wheel. The process demands not only great skill but much time and labour. The period required to reduce a stone of 24 or 30 carats to a regular form extended formerly to at least seven or eight months of constant work, and in the case of the Pitt diamond two years were needed; but the time is now greatly shortened by the use of machinery driven by steam. Jewellers have long cut diamonds in three forms—the brilliant, the rose, and tables. The brilliant is most esteemed, as giving highest effect to the lustre, and implying less reduction of the stone. It is, as it Were, a modification of the primary octahedron, the most common form of crystal, and is shown in its first form in figs. 6 and 7, ând with the full number of facets in figs. 8 and 9. Figs. 4 and 6 show the upper surfaces, with the table, or principal face, in the middle, surrounded by the bezil, or upper faces, lying between its edge and the girdle, or common base of the two pyramids. The lower facet corresponding to the table is named the collet, and the whole portion below the girdle the collet side. The portion removed to form the table (generally ⅛ths) and the collet (-⅛th) is shown in fig. 10 Brilliants are usually set open, both the upper or table side and the lower collet-side being exposed. The rose cut (upper view, fig. 11; lateral view, fig. 12) is given to stones which have too little depth to be cut as brilliants; it has the whole upper curved surface covered with equilateral tri angles. The table diamond, figs. 13 and 14, the least beautiful, is adopted for broad stones. o£ trifling depth, showing a series of four-sided facets above and below the girdle. Recently brilliants are cut in the star form
(taille à étoile), with the table above only one-fourth the diameter, and thus with less loss of weight.” There are also “mixed” or less regular forms used to suit the shape of the stone; and even splinters of diamond of - r ⅛ σ ∙ carat are facetted. In all the forms the girdle ought to be perfectly smooth, as a rough edge often appears through some of the facets as a flaw, and injures the brilliancy of the stone.
The value of diamonds is determined chiefly by their size, purity, colour, freedom from flaws or stains, and the skill with which they are manufactured. Their weight is reckoned by the carat, of four diamond grains, originally an Indian weight. In England the carat is estimated as = 3*174 grains troy; but it varies in different places, being, according to Schrauf, in Amsterdam = 205’70 milligrammes, in Florence = 197’20, in London = 205’409, in Madras = 207’353, in Paris = 205’50, and in Vienna = 206’13. The usual rule is that the value of the stone increases with the square of the weight in carats, and assuming £8 or £10 as the value of a cut brilliant of first quality in water and shape, weighing 1 carat, a similar stone of 2 carats would be worth four (2 × 2) times £8 or £10, iae. £32 to £40; one of 3 carats nine (3 × 3) times, or £72 to £90; and so in proportion. Fine brilliants, however, of the sizes most in demand sell much higher, or from £12 to £20 or more the first carat; whilst roses and tables are of considerably smaller value, and rough or uncut diamonds, generally sold in lots, fetch only about £2 or even less, the value being further diminished in all cases where the stones are “off colour,” that is milky or tinted, or imperfect in other respects. Still more important is the state of supply and demand, especially for the largest and most valuable stones, for which there are often very few purchasers, and their price is thus lower than the rule would imply. Even political events affect the price by bringing many into the market, as at the time of the first French Revolution. In 1873 Cape diamonds were stated to be worth—yellows under 5 carats, 40s. to 50s.; above that weight, £3 to £4 per carat; pure white stones under 5 carats, £3 to £4; and above 5 carats, £4 to £7, or more according to form or lustre. Fig. 15 shows the size of set stones round the girdle, the line indicating their depth, and the numerals the number of carats they may be expected to weigh.
Some diamonds are remarkable for their size or history. The largest undoubted diamond is the Orloff in the sceptre of the emperor of Russia, weighing 194¾ carats, and cut in the rose form, with a flat face below, resembling the half of a pigeon’s egg. According to one story, it formed the eye of an Indian idol, and was stolen by a French deserter; another is that it belonged to Nadir Shah of Persia, and on his murder came into the hands of an Armenian merchant, who brought it to Amsterdam. In 1772 it was sold to Count Orloff for the Empress Catherine for 450,000 silver roubles (£90,000), with an annuity of 4000 roubles and a title of Russian nobility. Second to it is the Regent or Pitt diamond (fig. 16), bought by Mr Pitt, the governor of Madras, in 1702, for about £20,000. He brought it to London, had it cut as a brilliant at, it is said, a cost of £3000, and sold it in 1717 to the regent duke of Orleans, for Louis XV., for 2∣ million francs, or £130,000; but it is estimated to be worth fully twice that sum. At the time of the first French Revolution it was sent to Berlin, but reappeared in the hilt of the sword of state worn by Napoleon I. It is considered as the finest and most perfect brilliant in Europe. It weighs 136∣ carats, but originally weighed 410 carats, and the fragments split or sawn from it when cut were valued at some thousand pounds. The third in weight is the Florentine, or Grand Duke, as it is named (fig. 17). It is of a fine yellow colour, oblong, and cut in rose. It is said to have been lost by Charles the Bold at the battle of Granson, and found by a Swiss soldier, who sold it for a few pence as a piece of rock crystal. It afterwards belonged to the grand duke of Tuscany, from whom it passed to the emperor of Austria. Its weight is usually given at 139∣ carats, but Schrauf finds its exact weight 133’16 Vienna carats, and its specific gravity at 19° C. 3’5213. The Koh-i-noor (fig. 18), the largest belonging to the British Crown, has also a singular history, corresponding to that of the country of its origin. The Indian legend tells that it was found in one of the Golconda mines near the Kishna river, and worn 5000 years ago by Karna, one of the heroes celebrated in the Mahabharata.
It passed through many hands to Baber, the founder of the Mogul dynasty, in 1526, and was shown by his successor in 1665 to Tavernier, the French traveller. He describes it then as of the shape of a half egg, and weighing 280 carats, having been thus reduced by an unskilled stone-cutter from 793f carats, which it once weighed. In 1739 it passed to Nadir Shah, the Persian invader of India, who gave it the name of Koh-i-noor, or Mountain of Light, and from his successors in 1813 to Runjeet Sing, the ruler of Lahore. In 1849, on the annexation of the Punjab to British India, the Koh-i-noor was also surrendered and presented to the Queen in June 1850. It was exhibited in the Great Exhibition of 1851, and then weighed 186-j⅛ carats, but has since been recut, with doubtful advantage, in the rose form, and is now 106 1 ⅛∙ carats. Its lower side is flat, and undoubtedly corresponds to a cleavage plane. Hence it has been conjectured that it and the Russian Orloff diamond are portions of the original stone belonging to the Great Mogul, whilst a stone of 132 carats, obtained by Abbas Mirza at the storming of Cooelιa, in Khorassan, in 1832, may be a third fragment. This portion was long used by a peasant as a flint for striking fire. The three united would have nearly the form and size given by Tavernier, and the Koh-i-noor would then surpass all known diamonds in its magnitude as in its eventful history.
It is not necessary to notice in detail other diamonds of smaller size, as the Sancy, of 53∣ carats, once the property of Charles the Bold, like the Austrian, and afterwards of Louis XIV. of France, but sold in 1830 for £20,000 to the emperor of Russia. In the Russian treasury are also the Shah of 86 carats, and the Polar Star of 40. Other noted ones are the Nassac of 89f carats (now recut, and 78 j), the Piggot of 82¾, and the Pasha of Egypt of 40 carats, which cost £28,000. Some are valued for other properties, as the Hope diamond, of a rare colour, a fine blue, and high brilliancy, estimated at £25,000,-though only weighing 44¾ carats. Red diamonds seem very rare, but there is a brilliant of 10 carats among the crown jewels of Russia, which cost £15,000, and in Dresden some very fine yellow stones, the largest of 29∣ carats.
Perhaps even more important is the use of the diamond for cutting glass, for polishing gems and other hard bodies, and recently by engineers for boring machines used in forming tunnels and artesian wells. The glaziers’ diamond is about the size of a pin’s bead, and is set in copper or brass. The curvature of the fracture faces gives a sharp edge that cuts and not scratches merely. Each costs about 12s. to 18s., and, as it will weigh only about ⅛⅛th carat, the price is higher than that used as gems. For polishing purposes the so-called “bort,” i.e. stones so imperfect in form and quality as to be useless for ornament, are broken down and crushed into diamond powder. The carbonado from Bahia is also employed both for polishing and for boring machines. In the latter the stones are fixed in a ring of steel, made to revolve with great rapidity, and kept cool by a current of water, wlιich also removes the detritus In consequence its price has risen lately from about Is. to 18s. or 20s. a carat.
The literature of the diamond is very extensive, and scattered through many works. Its history in ancient times is given by Pinder, De Adamante, Berlin, 1829; its general character in treatises on mineralogy and on precious stones—of the latter those by Jeffries, London, 1757; Mawe, ib. 1831; Emanuel, ib. 1865; and Streeter, ib. 1877; with the Edelsteinkunde of Kluge, Leipsic, 1860, and of Schrauf, Vienna, 1869, may be mentioned. More special are Murray, Memoir on the Diamond, London, 1831; Petzholdt, Beiträge zur Natur d. Diamanten, Dresden, 1842; Goeppert, Ueber Einschlüsse in D., Haarlem, 1864; and many papers in the journals and transactions of scientific societies. For its mode of occurrence may be consulted :—in India, Heyne’s Tracts, London, 1814; Ritter’s Erdkunde, Asien, vol. iv.; and many papers by Voysey, Adam, Franklin, Blandford, and others; in Brazil, Mawe’s Travels, London, 1812; Eschwege, Claussen, Spix and Martius, Gardner, Tschudi, &c.; for the Ural, Rose’s Heise, vol., i., but with much general information; for Australia, Liversidge, in Jour. Geol. Society; for the Cape, many papers in the Journals of Geol. Society and the Society of Arts, and. in the Geological Magazine, by R. Jones, Tennant, Dunn, Maskelyne, Flight, and Stow; and by Cohen in Leonhard and Geinetz’s Jahrbuch. ( J. NI.)
