Emeralds
Emerald is green precious and semi-precious stones and not, in the jewelry trade, the specific term of any gem mineral. Beryl, of the accepted green emerald hue, is the true or standard emerald. In the view of the mineralogical experts of the United States National Museum, recognition is accorded to five other varieties of “emeralds”; they are: Brazilian tourmaline, Congo-dioptase, Evening olivine, Oriental-corundum, and Uralian-garnet.
The green beryl, excepting in its color, is the same mineral as aquamarine, golden, and other variously colored beryls. One of the rarest of gems is a flawless emerald-hued beryl. The crystallization of the beryl is in the hexagonal system, usually long, and often having the prism faces more or less deeply striated vertically. The specific gravity of the transparent flawless beryl is 2.73, usually 2.69 to 2.70; hardness, 7.5 to 8; brittle; cleavage indistinct; fracture uneven to conchoidal; luster vitreous, sometimes resinous.
Beryl colors include emerald green to pale green, pale blue, pale yellow, honey, wine and citrine yellow, white, and pale rose-red. Pleochroism is unusually distinct, sometimes strong, in the emerald especially, which through the dichroiscope reveals two different shades of green. Beryl includes the emerald, aquamarine, goshenite, and davidsonite. The differences are principally in colour. Beryl is a silicate of the metals aluminium and beryllium, containing the oxide alumina in small amount, which is, however, a more important constituent in corundum, spinel, and chrysoberyl. There is some variation in beryl from different localities; the chemist Lewy, who analysed the beautiful emerald beryl that is found at Muzo in Colombia, South America, found: silica, 67.85; alumina, 17.95; beryllia,12.4; magnesia, 0.9; soda, .07; water, 1.66; and organic matter 0.12, besides a trace of chromic oxide. An analysis of a specimen of aquamarine from Adun Ohalon in Siberia by Penfield resulted in: silica, 66.17; alumina, 20.39; beryllia, 11.50; ferrous oxide, 0.69; soda, 0.24; water, 1.14, and a trace of litliia. The only acid which will attack beryl, so far as has been discovered, is hydrofluoric acid. Before the blowpipe beryl becomes white, cloudy, and fuses, but only with difficulty, at the edges to a white blebby glass.
The green beryl, excepting in its color, is the same mineral as aquamarine, golden, and other variously colored beryls. One of the rarest of gems is a flawless emerald-hued beryl. The crystallization of the beryl is in the hexagonal system, usually long, and often having the prism faces more or less deeply striated vertically. The specific gravity of the transparent flawless beryl is 2.73, usually 2.69 to 2.70; hardness, 7.5 to 8; brittle; cleavage indistinct; fracture uneven to conchoidal; luster vitreous, sometimes resinous.
Beryl colors include emerald green to pale green, pale blue, pale yellow, honey, wine and citrine yellow, white, and pale rose-red. Pleochroism is unusually distinct, sometimes strong, in the emerald especially, which through the dichroiscope reveals two different shades of green. Beryl includes the emerald, aquamarine, goshenite, and davidsonite. The differences are principally in colour. Beryl is a silicate of the metals aluminium and beryllium, containing the oxide alumina in small amount, which is, however, a more important constituent in corundum, spinel, and chrysoberyl. There is some variation in beryl from different localities; the chemist Lewy, who analysed the beautiful emerald beryl that is found at Muzo in Colombia, South America, found: silica, 67.85; alumina, 17.95; beryllia,12.4; magnesia, 0.9; soda, .07; water, 1.66; and organic matter 0.12, besides a trace of chromic oxide. An analysis of a specimen of aquamarine from Adun Ohalon in Siberia by Penfield resulted in: silica, 66.17; alumina, 20.39; beryllia, 11.50; ferrous oxide, 0.69; soda, 0.24; water, 1.14, and a trace of litliia. The only acid which will attack beryl, so far as has been discovered, is hydrofluoric acid. Before the blowpipe beryl becomes white, cloudy, and fuses, but only with difficulty, at the edges to a white blebby glass.
Beryl, like all other hexagonal crystals, is bi-refringent, but only to a small extent. The beauty of beryl, therefore, depends not upon a play of prismatic colours, but upon unusually strong lustre and a fine body-colour. The bright grass-green beryl is the emerald ; the pale varieties are styled precious or noble beryl. Aquamarine is pale-blue, bluish-green, or yellowish-blue; the yellowish-green variety is called aquamarine-chrysolite; jewellers call the yellow variety beryl and the pure golden-yellow golden beryl. The dichroism of all transparent varieties of beryl can often be discerned with the eye unaided by the dichroiscope ; this property usually suffices to clearly distinguish beryl from any imitations. A curious characteristic of the emerald beryl is that its colour is by no means always uniformly distributed through the body of the stone; the different colored portio DS may occur in layers or irregularly; when in layers the layers are usually perpendicular to the faces of the prisms.
The high esteem in which choice emeralds are held and the high cost of this gem are due in great part to the rarity with which a gem approximating perfection occurs. Most of the grass-green beryl crystals are cloudy and dull; these disqualifications are due to fissures and cracks, but also to infinitesimally small enclosures of foreign matter, either fluid or solid, such as scales of mica. When clouded by fissures emeralds are called by jewelers " mossy." A "perfect" (approximately of course) emerald- beryl stone is worth nearly, sometimes fully, as much as a fine natural ruby and more than a diamond that is, a stone of one carat or thereabouts, while large stones are so rare that they bring fancy prices out of all proportion to their size. The average emerald beryl fit for cutting is but a small stone. Tradition and unscientific accounts tell of phenomenally large emeralds, but one of the largest and finest actually known to exist belongs to the Duke of Devonshire; this is a natural crystal, measuring two inches across the basal plane, and weighs 8 9/10 ounces, or 1350 carats; in colour, transparency, and structure it is almost without a fault. This fine stone was found in the emerald mines at Muzo in Colombia, South America. Another large crystal known belongs to the Czar of Russia; its measurements are reported to be twenty-five centimetres (nearly ten inches) in length and twelve centimetres in diameter. The character of each piece of the rough beryl placed in the hands of the lapidary decides what cut shall be applied to an emerald. Small stones are usually cut as brilliants or rosettes, while the large ones are sometimes cut as a simple table stone, or more generally step-cut with brilliant facets on the upper portion. Cut gems of good colour and transparency are mounted in an open setting; paler stones were formerly, in Europe, reinforced with a green foil beneath them, while fissured or faulty stones were mounted in an encased setting with the bottom blackened. As natural crystals of beryl are large the gems are often extracted from the mass by expert and skilful artisans who saw the crystals into the desirable sizes. The emerald beryl might be truly said to be a precious stone of strong individuality, for. besides its characteristic of an uneven and irregular distribution of colour, it is unique geologically, for it occurs exclusively in its primary situation, that is, in the rock in which it was formed. It is one of the minerals characteristic of crystalline schists, and is frequently found embedded in mica schists and similar rocks. The magnificent beryls found at Muzo, Colombia, however, are an exception; there the emeralds are embedded in calcite veins in limestone. Emeralds are never found in gem gravels, like diamonds, rubies, sapphires, and other precious stones. The ancient source of the emerald was Ethiopia, but the locality is unknown. From upper Egypt, near the coast of the Red Sea and south of Kosseir, came the first emeralds of historic commerce. There is a supposition that the emerald beryl was first introduced commercially into Europe just prior to the seventeenth century from South America. Emeralds had been found before this, however, in the wrappings of Egyptian mummies and in the ruins of Pompeii and Herculaneum. Ancient Egyptian emerald mines on the west coast of the Red Sea were rediscovered about 1820 by a French explorer, Cailliaud, on an expedition organised by Mehemet Ali Pasha ; the implements found there date back to the time of Sesostris (1650 B.C.). Ancient inscriptions tell that Greek miners were employed there in the reign of Alexander the Great; emeralds presented to Cleopatra, and bearing an engraved portrait of the beautiful Egyptian queen, are assumed to have been taken from these mines. Cailliaud, under permission of Mehemet Ali, reopened the mines, employing Albanian miners, but, it is supposed because only stones of a poor quality were found, the work was soon and suddenly given up. The Spanish conquistadores found magnificent emeralds in the treasure of both Peru and Mexico, but none are now found in those countries. An immense quantity of emeralds, many of them magnificent, and a large proportion of which are probably still in existence in Europe, was sent to Spain from Peru. The only place in the new world that the Spanish found emeralds by prospecting for them in the earth, was in Colombia or New Granada; perhaps the gems of the Aztec sovereigns and the Incas came from there. The Spaniards first learned of the existence of the Colombian emeralds on March 3, 1537, through a gift of emeralds by the Indians, who, at the same time, pointed out the locality from which they were taken; this spot, Somondoco, is now being mined by an English corporation, although only second-class stones have been found there by these modern emerald miners. Muzo, where the present supply of the world's finest emeralds is mined, is about one hundred miles distant in the eastern Cordilleras of the Andes on the east side of the Rio Magdalena in its northward course. The only other locality of importance where emerald beryls are now found is about fifty miles east of Ekaterinburg in the Ural Mountains, Siberia, where Uralian chrysoberyl, or alexandrite, is found. The grass-green beryl is also found in an almost inaccessible locality in the Salzburg Alps. Fine emeralds have been found in the United States, the most notable locality at Stony Point in Alexander County, North Carolina, but the supply at this place seems to be exhausted. The name "emerald" applied indiscriminately to green transparent, translucent, and even opaque stones, complicates, to the inexpert, everything about the emerald question; for instance, it was long assumed that emeralds came from Brazil and green stones were called " Brazilian emeralds." There is no authentic proof that a true emerald was ever found in Brazil, and it is supposed that green tourmalines found there account for the " Brazilian emerald " myth. In ancient times the name emerald was applied to green jasper, chrysocolla, malachite, and other green minerals. There is still a custom of calling stones other than beryl "emerald," with an explanatory prefix. Thus, Oriental emerald is green corundum ; " lithia emerald " is hiddenite, a green mineral of the pyroxene group occurring associated with the emerald beryl in North Carolina. "Emerald-copper" is dioptase, the beautiful green silicate of copper. Among the green minerals sometimes sold under the name of emerald are: the green corundum, demantoids, or green garnets, hiddenite, diopside, alexandrite, green tourmaline, and sometimes chrysolite and dioptase. These minerals are all of higher specific gravity than beryl and all can be distinguished from beryl emeralds by tests possible to the scientific gem expert.
The high esteem in which choice emeralds are held and the high cost of this gem are due in great part to the rarity with which a gem approximating perfection occurs. Most of the grass-green beryl crystals are cloudy and dull; these disqualifications are due to fissures and cracks, but also to infinitesimally small enclosures of foreign matter, either fluid or solid, such as scales of mica. When clouded by fissures emeralds are called by jewelers " mossy." A "perfect" (approximately of course) emerald- beryl stone is worth nearly, sometimes fully, as much as a fine natural ruby and more than a diamond that is, a stone of one carat or thereabouts, while large stones are so rare that they bring fancy prices out of all proportion to their size. The average emerald beryl fit for cutting is but a small stone. Tradition and unscientific accounts tell of phenomenally large emeralds, but one of the largest and finest actually known to exist belongs to the Duke of Devonshire; this is a natural crystal, measuring two inches across the basal plane, and weighs 8 9/10 ounces, or 1350 carats; in colour, transparency, and structure it is almost without a fault. This fine stone was found in the emerald mines at Muzo in Colombia, South America. Another large crystal known belongs to the Czar of Russia; its measurements are reported to be twenty-five centimetres (nearly ten inches) in length and twelve centimetres in diameter. The character of each piece of the rough beryl placed in the hands of the lapidary decides what cut shall be applied to an emerald. Small stones are usually cut as brilliants or rosettes, while the large ones are sometimes cut as a simple table stone, or more generally step-cut with brilliant facets on the upper portion. Cut gems of good colour and transparency are mounted in an open setting; paler stones were formerly, in Europe, reinforced with a green foil beneath them, while fissured or faulty stones were mounted in an encased setting with the bottom blackened. As natural crystals of beryl are large the gems are often extracted from the mass by expert and skilful artisans who saw the crystals into the desirable sizes. The emerald beryl might be truly said to be a precious stone of strong individuality, for. besides its characteristic of an uneven and irregular distribution of colour, it is unique geologically, for it occurs exclusively in its primary situation, that is, in the rock in which it was formed. It is one of the minerals characteristic of crystalline schists, and is frequently found embedded in mica schists and similar rocks. The magnificent beryls found at Muzo, Colombia, however, are an exception; there the emeralds are embedded in calcite veins in limestone. Emeralds are never found in gem gravels, like diamonds, rubies, sapphires, and other precious stones. The ancient source of the emerald was Ethiopia, but the locality is unknown. From upper Egypt, near the coast of the Red Sea and south of Kosseir, came the first emeralds of historic commerce. There is a supposition that the emerald beryl was first introduced commercially into Europe just prior to the seventeenth century from South America. Emeralds had been found before this, however, in the wrappings of Egyptian mummies and in the ruins of Pompeii and Herculaneum. Ancient Egyptian emerald mines on the west coast of the Red Sea were rediscovered about 1820 by a French explorer, Cailliaud, on an expedition organised by Mehemet Ali Pasha ; the implements found there date back to the time of Sesostris (1650 B.C.). Ancient inscriptions tell that Greek miners were employed there in the reign of Alexander the Great; emeralds presented to Cleopatra, and bearing an engraved portrait of the beautiful Egyptian queen, are assumed to have been taken from these mines. Cailliaud, under permission of Mehemet Ali, reopened the mines, employing Albanian miners, but, it is supposed because only stones of a poor quality were found, the work was soon and suddenly given up. The Spanish conquistadores found magnificent emeralds in the treasure of both Peru and Mexico, but none are now found in those countries. An immense quantity of emeralds, many of them magnificent, and a large proportion of which are probably still in existence in Europe, was sent to Spain from Peru. The only place in the new world that the Spanish found emeralds by prospecting for them in the earth, was in Colombia or New Granada; perhaps the gems of the Aztec sovereigns and the Incas came from there. The Spaniards first learned of the existence of the Colombian emeralds on March 3, 1537, through a gift of emeralds by the Indians, who, at the same time, pointed out the locality from which they were taken; this spot, Somondoco, is now being mined by an English corporation, although only second-class stones have been found there by these modern emerald miners. Muzo, where the present supply of the world's finest emeralds is mined, is about one hundred miles distant in the eastern Cordilleras of the Andes on the east side of the Rio Magdalena in its northward course. The only other locality of importance where emerald beryls are now found is about fifty miles east of Ekaterinburg in the Ural Mountains, Siberia, where Uralian chrysoberyl, or alexandrite, is found. The grass-green beryl is also found in an almost inaccessible locality in the Salzburg Alps. Fine emeralds have been found in the United States, the most notable locality at Stony Point in Alexander County, North Carolina, but the supply at this place seems to be exhausted. The name "emerald" applied indiscriminately to green transparent, translucent, and even opaque stones, complicates, to the inexpert, everything about the emerald question; for instance, it was long assumed that emeralds came from Brazil and green stones were called " Brazilian emeralds." There is no authentic proof that a true emerald was ever found in Brazil, and it is supposed that green tourmalines found there account for the " Brazilian emerald " myth. In ancient times the name emerald was applied to green jasper, chrysocolla, malachite, and other green minerals. There is still a custom of calling stones other than beryl "emerald," with an explanatory prefix. Thus, Oriental emerald is green corundum ; " lithia emerald " is hiddenite, a green mineral of the pyroxene group occurring associated with the emerald beryl in North Carolina. "Emerald-copper" is dioptase, the beautiful green silicate of copper. Among the green minerals sometimes sold under the name of emerald are: the green corundum, demantoids, or green garnets, hiddenite, diopside, alexandrite, green tourmaline, and sometimes chrysolite and dioptase. These minerals are all of higher specific gravity than beryl and all can be distinguished from beryl emeralds by tests possible to the scientific gem expert.
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