DIAMOND, adamas of the ancients, almas of Persia, and heera of Hindustan, is the most brilliant of gems; and although known from the remotest times, if we may judge by the casual notice made of it in Scripture, it had in the earlier periods of history obtained little more than a name. Pliny states that it bore a price above all things in the world, and was known to very few except princes and crowned heads. His meagre remarks on this gem are even less satisfactory than those upon almost any other; which affords another reason to conclude that the diamond still remained in his time an object of great rarity. The localities quoted by Pliny appear to be quite erroneous, at least subsequent observations give us reason to think so.

Up to the commencement of the eighteenth century diamonds were wholly derived from India, where they were found in detached crystals, accompanied with grains of gold, amongst metallic sand washed down from surrounding mountains. In 1728 a similar territory, loaded with the two most valuable substances in nature, was discovered on the southern continent of the New World. When in pursuit of gold, crystals of diamond were often found; but the labourers being ignorant of their value, laid them aside as curiosities. A miner, who is said to have arrived in Brazil at this time, first directed attention towards them; and, without attempting to appropriate his discovery to his own aggrandisement, he led his comrades to turn their pursuit to the more engaging object. It soon, therefore, attracted the notice of the government, and was shortly afterwards taken possession of in name of the sovereign.

Hitherto the supply of diamonds was entirely confined to Hindustan and the island of Borneo; and, as might reasonably be expected, the opening of a new field, the extent of which was as yet wholly unknown, could not fail to affect the market. The discredit which was at first thrown upon the accounts from Brazil, as also on the purity and perfection of the stones, repressed the fears of the Asiatic dealers, and the increased demand after the purchase of the Pitt diamond, a circumstance which no doubt rendered that gem far more recherche at the gay and luxurious court of France, all tended to increase the demand, and keep it more upon an equilibrium with the increased supply than could possibly have been expected. At a subsequent period, no doubt, the revolution of France interfered with the value of jewels; but the surplus thus produced was soon absorbed by the wealth of Britain, and diamonds of the first water for a long time maintained their ground.

At the present day this perhaps cannot be said to hold good. As a commercial commodity, diamonds must have suffered depression like all others, and may perhaps be valued at from twenty-five to thirty per cent, particularly those beyond the smallest sizes, under the prices which they bore in the times of Tavernier; although Mawe appears to have been anxious to inculcate a different doctrine. After his examination of the Brazilian district, he says there would be no difficulty in calculating the period requisite to work out the whole of the diamond ground in that country; and as many of the mines of Hindustan are considered as exhausted, the period must come sooner or later when diamonds will be no longer to be had.

In both countries the gem is confined within the limits of the tropics. In India, Golconda has always been cited as one of its principal repositories, although none was ever found in the immediate vicinity of that fortress, from the circumstance perhaps of the geological character of the neighbourhood, which is entirely syenitic. It may have arisen, however, from the fact, that the diamond mines of Raolconda and Gance Purteeal were situated in the territory of the Kootub Shahee kings of Golconda. When that dynasty was overthrown, and their country occupied by the officers of the Mogul emperors, Golconda ceased to be the capital, and Hyderabad, which is only a few miles distant, became the occasional seat of the new government. The territory in which the mines are situated has since been ceded to the East India Company. It lies near Condapilly, on the northern bank of the Kistna, about fifty miles from the sea, and near the Pass of Bezoara, where the river appears at some period to have forced its way through a chain of hills, and to have emptied an extensive lake which had existed to the westward of them. All attempts to work them have been abandoned, as the produce has ceased to refund the expense of labour. The localities of the diamond in Hindustan are so various that it would be almost endless to enumerate them. Those on the Mahanuddy, with those on the Kistna and at Malla-villy, north-west of Ellore, may be mentioned as probably the most productive of this beautiful gem. The island of [7:8:4]Borneo is the only other eastern locality which can boast of its production. It occurs at Pontiana, in that island, directly under tlw line, and at Benjarmassin, about three degrees south of the equator. Here it is said to be of a quality superior to that of the gems found in the other Indian localities, and to be distinguished in consequence by the name of Landah, the place they are found in. Here also the diamond occurs in alluvial soil, accompanied with gold. One diamond was found about a century ago, of 367 carats, supposed to be now in the hands of the chief of Pontiana.

From Heyne’s account of the working of diamond mines in Hindustan, it seems to afford a very miserable livelihood. He 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 eighteen inches, consists of sand, gravel, and loam; next there is a deposit of stiff black clay or mud, of about four feet; and next the diamond bed, which is distinguished by a mixture of large rounded stones. It is from two to two and a half feet thick, closely cemented together with clay. Sometimes this stratum is covered with calcareous tuffb. 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, and, when it comes to be again wrought over more carefully, may give risÈ to the absurd fancy of regeneration.

The miners, Μ. Voysey (Asiatic Researches, vol. xv. p. 120) says, are of opinion all over India, that the chips and small rejected pieces of former searchers actually increase in size, and in process of time become large diamonds; and he finishes his paper, by hoping that some future mineralogist would ascertain whether there were any foundation for the vulgar opinion of the continual growth of the diamond; particularly as he hoped at some future period to produce undeniable proof of the re-crystallization of amethyst, zeolite, and felspar, in alluvial soil. This respectable gentleman did not live to bring forward his proofs; but had he been doomed to arrive at the age of the patriarchs of old, we are of opinion he would have been puzzled to produce them.

In Brazil, the diamond is more confined to one spot than in India. The district of Minas Geraes comprehends, as far as we yet know, the whole of the diamond grounds hitherto discovered in the New World. There the workings appear to be carried on more systematically than in India. The operations at the Serra do Frio we have already described in the article Brazil (vol. v. p. 199). The Serra do Frio, or cold mountain, is a mountainous platform, having an elevation of from sixteen to eighteen hundred metres. The district over which the diamonds are searched for, extends about sixteen leagues from north to south, by about eight from east to west. It is situated twelve leagues north of Tejuco, on the river Tigitouhonha, which falls into the river San Francisco. By the decomposition of the granite, an agglomerate is formed, composed of rounded white quartz pebbles, and light-coloured sand, to which the natives give the name of cascalho; and it is in this substance that the diamonds are found, along with gold, which is sometimes crystallized. It is exactly similar to some of the samples of the diamond deposits of Hindustan sent to the Royal Society of Edinburgh by Mr Swinton, but differs considerably from others, where a conglomerated sandstone of considerable tenacity has in several instances been sent, as the matrix of the diamond.

From any thing w e are yet able to judge, it does not appear that the diamond has ever yet been seen in a matrix which could be esteemed its original position. Heyne has given two coloured engravings of diamonds in the ma- . trix, and they have the merit of representing very faithfully specimens of this description we have seen at home; but they are in all probability only diamonds accidentally agglutinated in ferruginous matter having no character of a rock. The Musnuddy, which joins the Mahanuddy, is mentioned as affording an indication which might lead to a favourable result in such an investigation. At its confluence with the Maund River, near Chunderpoor, and not farther down than Sonpoor, it is only on the left bank of the river that diamonds are found. Hence the Maund is the point at which the examination should commence; and if the country can be effectually penetrated, it would be well worthy the attention of some enterprising mineralogist.

We have no satisfactory geological account of any of the diamond countries; a slight sketch by Voysey, in the article above quoted, is the best that we can refer to. He particularly alludes to a range of hills, called the Nalla Malla, or Blue Mountains, about Cummum, on the Gun-lacummum river, which are composed of schistose rocks, of all varieties, from clay-slate to pure limestone, accompanied with quartz rock, sandstone, sandstone brescia, flinty slate, hornstone slate, and a tuffaceous limestone, containing imbedded, rounded, and angular masses of all these rocks. These are bounded on all sides by granite, which appears to pass under and form the base. The only rock of this formation on which the diamond is found is the sandstone brescia. “I have as yet,” says he, “only visited the rich mines of Banaganpilly (lying in Heyne’s map in 78° 4' by 15° 4'), where the brescia is found under a compact sandstone rock, differing in no respect from that which is found under other parts of the main range. It is composed of a beautiful mixture of red and yellow jasper, quartz, calcedony, and hornstone, cemented together by a quartz paste. It passes into puddingstone, composed of rounded pebbles of quartz, &c. cemented by an argillo-calcareous earth, of a loose friable nature, in which the diamonds are most frequently found.”

Heyne states, that in some of the mines in India the diamonds are found entirely broken or crushed, and only of value for pounding; but at the same time thinks it must be owing to carelessness. He mentions also that the diamonds of Cuddapah are carried to Madras to be used for the same-purpose, and the price he quotes for a carat of stones fit for brilliants is only seven rupees.

No crystal in nature is more beautiful than that of the diamond. It is sometimes so pure and so pellucid, with its angles and faces so perfectly symmetrical, as to shine like a dew-drop in the rays of the sun. Its primitive form is that of the equilateral octahedron. It passes into the dodecahedron and the cube, presenting modifications in each. The colourless diamond of the first water is the most valuable; but very fine diamonds sometimes present a deep red tinge, also yellow, orange, green, blue, and black. Those which have a slight tint of yellow are often remarkably brilliant, and are said to be of a superior hardness.

The value of diamonds is always calculated in carats, which consists of four grains; but it must be remembered, that the diamond grain differs from the Troy grain, as it takes five of the former to weigh four of the latter, or more exactly one carat = 3∙174 gr. Troy.

In valuing diamonds, either rough or cut, the practice is to take the weight in carats, to square that weight, and [7:8:5]then to multiply the product by such a rate of price as may correspond to the state and quality of the stone; thus, if a natural crystal of diamond be clear, without flaws, and of a favourable shape, the price by which the square of its weight should be multiplied is L.2; so that if the stone weigh one carat, its value will be L.2, if two carats, 2×2-4, and 4 X 2 = 8, or a stone of two carats is worth L.8. A stone of ten carats, in the same way, will give 10 × 10 = 100, and 100 × 2 = L.200, the value of a perfect rough diamond of this weight.

If the diamond has been worked into a brilliant of just proportions, the same rule is observed of squaring the weight in carats; but a much higher price is used as the multiplier of the product; as L.8 is considered to be the proper multiplier when the stone is perfect in water and shape. Thus a diamond of 5ļ-carats gives 301- as its square, and this multiplied by 8 makes L.242 as its price. If the stone has been worked into the form which is termed a rose, L.6 is used as the multiplier; and if it be of the form termed table-cut, it is still lower.

Considerable modifications, however, must be made in these multipliers, according to the quality of the diamonds and the state of the market. If a brilliant be what is termed “off colour,” that is, not absolutely colourless, or if it be in any other way imperfect in shape or purity, a corresponding diminution must be made in the multiplier. Thus a brilliant with a yellow or a milky hue, or with a small speck or flaw, may not be multiplied by more than L.4, L.5, or L.6, according to the nature or extent of the imperfection. The state of the demand in the market must likewise have great influence. At present the demand for good brilliants of one carat and under is greater in proportion to the supply than for heavier stones, and such stones will therefore sometimes cost L.10 the carat; whilst there being fewer purchases for the larger sizes, they may often be had in commerce at a lower rate than has been mentioned above.

The finest known diamonds arc as follow:

That of the crown of France (Pitt diamond), weighing 136^ carats, the value of which, taken according to the above çule, would be L.14l,058. The dimensions of this fine stone are stated to be,
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That of the Grand Duke of Tuscany (now Austrian), weighing 139∣ carats, valued as above at L.153,682.

That of the Emperor of Russia, weighing 195 carats. This diamond is rose cut.

That of the Great Mogul, weighing 279-A∙ carats, also rose cut.

That of the King of Portugal, weighing 1680 carats, being rough, not less than L.5,644,800.

It is consequently quite evident that this rule can obtain only among diamonds of moderate size; and if it should establish something by which a price may be named, all else must be left to subsequent arrangement.

Of the remarkable diamonds we have enumerated, the first is that known by the name of the Regent or Pitt diamond. It was found at Pasteal, in the Golconda district. It was imported into this country by Mr Pitt, governor of Madras, who purchased it from a native for 48,000 pagodas, about L.20,400 at the exchange of the day, and after being offered to different crowned heads in Europe, was purchased by the regent of France in 1717 as a jewel for the crown. It was placed by Napoleon in the hilt of the sword of state, and, according to Brard, the price paid for it was 2,250,000 francs; Jeffreys calls it L.125,000, and other authors say L.130,000. Any of these, however, although by much the largest price ever paid for any jewel, is not equal to the rule of value. This is esteemed the finest and most perfect diamond known.

The second was purchased for a bit of rock-crystal, on a stall in the market-place of Florence, at the cost of a few pence; it is of a beautiful lemon-yellow colour, and is now in the possession of the house of Austria. The diamond mentioned as the property of the Emperor of Russia ornaments the top of his sceptre. It is of the size of a pigeon’s egg, and is said to have been the eye of an Indian idol pillaged by a deserter from the French service, who had the address to get himself installed as a priest in the service of the Malabar deity at Seringham, as narrated by Dutens. The Empress Catherine purchased it for L.90,000, together with an annuity of L.4000.

The Great Mogul is described by Tavernier as an irregularly-shaped diamond, but cut and polished. It was found at Colore, in the district of Golconda, in the year 1550; and is said to have weighed 900 carats before cutting, but this appears a most enormous sacrifice. Of the Brazilian diamond some suspicions have been entertained. It has been insinuated that it is only a mass of very fine white coloured topaz, and it is not likely that the king of Portugal will run the hazard of ascertaining the fact.

The supply of diamonds from Brazil, according to Baron d’Eschwege, during the eighty-four years from 1730 to 1814, was at the rate of 36,000 carats per annum; but the return from the registers of the administration of the diamond mines from 1800 to 1806 was only 19,000 carats. It is also added, that the revenue derived by government during the first period was only eighteen or nineteen francs the carat, whilst from forty to fifty were obtained during the last; a certain indication of a diminished supply. A singular circumstance is noticed with respect to the uniformity of the diamond ground of Do Frio. The same cubic mass of cascalho will yield, on washing, pretty nearly the same number of carats, in large or small diamonds, so that the superintendent can calculate on the probable produce of the washing.

Large stones do not abound in Brazil, but there are some of considerable dimensions. Mawe mentions one from the little rivulet D’Albaite of 120 carats, but they do not often exceed from eighteen to twenty.

The prices of diamonds quoted by Heyne, who visited with a scrutinizing eye the principal mines of Hindustan, differ from those laid dow n by the rule of Tavernier and Jeffreys. Without attempting to reconcile them, we shall quote the value which the Hindus put upon what they consider as the best, and denominate the Brahma diamond; it is sold by the manjalin, which is equal to two carats, and each carat at the price of ten pagodas.
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He adds that these are the prices of stones free from speck, flaw, or crack. Cut stones are valued in a different way.

The most remarkable circumstance in the history of the diamond is to be found in the nature of its composition. This proud, this imperial ornament, which has ever occupied the summit of the diadem, this most brilliant of gems, and hardest of all known bodies, is, after all, but a morsel of charcoal, which has been made to yield to the rays of the sun, and dissolve into a noxious vapour. As early as 1607, Boetius de Boodt threw out the hint that [7:8:6]diamond was inflammable. In 1673 Boyle discovered that when it was exposed to a great heat it was dissipated into acrid vapour. In 1694, the experiments of Boyle were confirmed by those of Cosmo III. Grand Duke of Tuscany, with his celebrated burning glass. About the same time, but whether before or not is uncertain, Sir Isaac Newton was led, from the great refractive power of the diamond, to pronounce it “an unctuous substance coagulated.” Lavoisier proved it to be composed of carbon, by throwing the sun’s rays concentrated by a powerful lens upon a diamond inclosed in a vessel with oxygen gas; when the diamond and the oxygen disappeared, and carbonic acid was generated. Sir George Mackenzie repeated the experiments of Boyle in 1800; and, finally, when Sir Humphry Davy visited Florence in 1814, the experiment of the grand duke was performed again with the same lens; and mineralogists no longer hesitated to place the gem amongst inflammable bodies.

According to Ellicot, the specific gravity of Brazil diamonds is 3∙513, and of India diamonds 3 ’ 519. The former is the mean of four, the latter of ten experiments.

Diamond cutting was little understood till 1476, when an artist of the name of Berghen, residing at Bruges, introduced the practice of using diamond powder for forming and polishing the facets. Holland, in consequence, long maintained a monopoly of this trade; and to this day the smaller diamonds are almost entirely manufactured for the European market, at Amsterdam. The Pitt diamond was, however, cut and polished in London, as most of the larger sized stones continue to be. It is a very laborious and tedious operation. The grinding into the required form is entirely done by the hand. Two stones are cemented to the ends of tool handles, and rubbed with a powerful pressure against each other, a leaden model being first taken of the rough stone intended to be cut. The faces are thus determined. The two stones are then rubbed together over a little metal box haying a double bottom, the upper one being loose and perforated with small holes, through which the diamond dust passes, and is carefully preserved. The desired form being thus obtained, the dust is afterwards used in polishing the faces of the diamond, mixed up with sweet oil, on a common lapidary’s wheel, and the brilliancy of the gem brought out. The period of constant work required to reduce a stone of between twenty-four and thirty carats to a regular form will extend to at least seven or eight months constant work. The Pitt diamond was said to occupy two years. From the outline in Plate CCII. fig. 1, there was a great deal of extraneous matter to reduce, and that space of time may very likely have been required. When the mass to be removed is of such a size as to render it of importance to keep it entire, the piece is cut off by means of a steel wire, extended on a bow of cane or whalebone, anointed with diamond powder. This process is very commonly adopted in India. The diamond is sometimes also split by means of a chisel under a sharp stroke of a hammer; but this means requires great firmness of mind and dexterity of hand, for a valuable stone is sometimes destroyed by an unlucky blow.

The forms into which the diamond is cut are the brilliant, the rose, and the table. The first is composed of a principal face, which is called the table, surrounded by a fringe composed of a number of facets, which is all that is visible above the bezil when set. The proportion for the depth should be half the breadth of the stone, terminated with a small face, parallel to the table, and connected with the surface by elongated facets. As the octahedron is the most common natural form of the stone, and the brilliant cut being by far the most advantageous in point of effect, and the most economical form that can be adopted, it is hence preferred. The others are suggested by the shape of the mass.

The rose is entirely covered with facets on the surface, and is flat below. The table form is adopted in consequence of the shape of the mass, whether crystal or fragment, and produces the least effect. It is principally used in India, where the native jewellers cleave stones into plates, having often a large surface with little proportioned weight or brilliancy, except at the edges, which are ornamented by being cut into facets. The great diamond of the Mogul emperor, called Derriah Noor, is of this description; that called Koh-é-noor is rose-cut.

Much of the value of diamonds depends on the cutting of the stone. A late celebrated philosopher, who required a piece of diamond for philosophical purposes, found a large mass in the hands of a jeweller. It was of an awkward form, and presented a flaw which very greatly deteriorated its value, as, in consequence of the refraction and reflection which took place within the mass, the flaw seemed to occupy nearly the whole of the interior. The gentleman, however, was not afraid. He paid a large sum for the stone, directed the workman in cutting it, amputated the piece he wanted, separating the flaw, and sold the remainder back to the jeweller, after being properly cut and polished, for double the price he paid for it.

Hopes were recently excited, that a new diamond district had been discovered in Siberia by the celebrated traveller Humboldt. He thought he had met with appearances in a territory belonging to Count Demidoff, analogous to that of Minas Geraes, and recommended a search for the gem. But as two years have since elapsed without any confirmation of this suggestion, the old localities of Asia and Brazil are likely to remain without competition.

Explanation of the Plate, No. CCII.—The three figures at the top, No. 1, 2, 3, are representations of the Regent or Pitt diamond, the Great Mogul, and the Grand Duke, of the full size and form. No. 4 presents the brilliant cut, looked at perpendicularly. No. 5, the same sidewise. No. 6 and 7 also represent the brilliant before it undergoes the process of re-cutting. No. 8 and 9 are the vertical and lateral appearances of the rose-cut diamond; and No. 10 and 11, that of the table-cut. The scale No. 12 exhibits the sizes of the set diamond within the bezil, together with the depth of the stone, and the number of carats a diamond of that size is likely to weigh. This estimate can only be an approximation to the exact weight; but the weight of a set stone may thus be very nearly ascertained. No. 13 is the figure of the octahedral diamond seen perpendicularly, with the table traced where the stone should be cut; and No. 14 is the same crystal seen laterally, with the table and the opposite face also traced. By these figures it will be seen how much more advantageous it is to adopt the brilliant form than any other.

Diamonds have been imitated with great success by the French artists. To this composition, to which they give the name of strass, they not only communicate the adamantine lustre of the zircon, but succeed in giving it such a similitude to the real stone in all respects, hardness excepted, that it is nearly impossible for unpractised eyes to detect the difference. Recently quartz has been used with great effect to form the faces of factitious stones.

Diamond used by Glaziers, is an instrument made of steel or iron, into the point of which a diamond is introduced and fixed by solder. Care must be taken to place the gem so that, by applying the instrument in a particular position, the angle of the crystal will come in contact with the glass.

Diamond, in Heraldry, a term used for expressing the black colour in the achievements of peerage.
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Guillim does not approve of blazoning the coats of peers by precious stones instead of metals and colours; but the English practice allows it. Morgan says the diamond is an emblem of fortitude.

Diamond Harbour, a harbour in the western branch of the Ganges, on the Hooghly river, about thirty-four miles below Calcutta in a straight line, but much more by the windings of the river. Here the Company’s ships generally unload, and take in great part of their homeward bound cargoes. There are mooring chains for their accommodation, and storehouses on shore; and in the adjacent villages, consisting of a few thatched houses, with some petty shops, provisions may be purchased. But the place is very unhealthy, especially during the periodical rains in July, August, and September, owing to the exhalations from the swamps, and the heavy dews which fall at night. The country on both sides of the river is infested with tigers.

Diamond Island is situated on the east side of the Bay of Bengal, twelve miles south from Cape Negrais. It is about a mile and a half long, by one mile broad; low, covered with wood, and surrounded by shoals, which render it dangerous for boats to land. It has fresh water, and abounds with turtle. It belongs to the Burmese, and is uninhabited. Long. 94. 12. E. Lat. 15. 51. N.