Manual of Precious Stones and Gems – Westropp

/books/westropp-manual-of-precious-stones-and-gems/westropp-manual-of-precious-stones-and-gems

NEPHRITE—JADE

An anhydrous silicate of magnesia. The colour of jade varies from a creamy white to a dark olive-green. The hardness of this stone renders it excessively difficult to cut and polish. Jade is translucent, very tough, breaking with a coarse, splintery fracture. Jade is found in Egypt, China, from the quarries of Kuen-lun, New Zealand, North America.

China furnishes ornamental vases and cups of this stone, elaborately carved, where the variety called Yu is highly prized. (8)

(8) Between Yurkland and Ladak, and about a mile from Gulbusha, we found numerous remains of the old jade works, piles of rough  broken lumps of jade, which had been thrown aside, also small caves and borings in the alluvial bank, where they had dug out the ‘ waterdeposited ‘ pebbles of jade, the Yeshamba-i-ab, which from its purity and compactness is considered the most valuable. The quarries extend over an irregular belt of a mile or so in length, and 200 or 300 feet in breadth along the mountain side, and in this space there are the entrances of at least 100 mines.

(8) ” Jade-rocks were often many feet in thickness. The colour of tie cut surface varies from a light straw-green, through the different shades of green up to nearly black. The latter resembles the nephrite of Siberia.”—”

(8) The Jade Quarries of Kuen-lun,” by Cayley.  Macmillan’s Magazine, Oct., 1871.
Dr. Rennie (” Peking and the Pekingese,” vol. i. p. 291) mentions seeing at Peking a very rare variety of green jade, to which greatvalue is attached. It was termed Fate-su-ee.

It is carved into handles of swords and daggers in India. Cups of a mottled variety come from Siam. In New Zealand a variety called ”  poenamu ” is fashioned into clubs (meri), hatchets, idols (called Tiki). The pure translucent kind is made into ear-pendants, and worn by  the chiefs. It is also used in New Caledonia for hatchets. The name nephrite is from the Greek ve<£pds, kidney, in allusion to the belief entertained in former times of its influence in frequently curing diseases of the kidney.

The French name jade is said to be derived from hi-jada, the Spanish word for kidney. According to Estner it is from the name  igida, by which it is called in India.

JADEITE.

A silicate of alumina and magnesia. It is an opaque stone, of a green colour mixed with white. It is often used in India for sword-handles and other ornaments. The Chinese variety is of a delicate green. The rude figures of green colour, not transparent, mixed with white, carved and skilfully polished, found in tombs in Mexico, are of this stone. It was named Chalchituitl by the Aztecs, who held it in high estimation. The elaborate clasp fastening the monarch Montezuma’s imperial robe was of this stone. It was supposed by the Spaniards to be an inferior emerald (baja esmeralda).

TURQUOISE

A phosphate of alumina, tinted with phosphate of iron, and phosphate of copper, Turquoise is of a beautiful sky-blue. Turquoise occurs reniform, stalactitic. This is the true turquoise de la vieille roche, the Oriental or mineral kind. The best Turquoise comes from Persia, from the mines of Ansar, near Nishapur, in Khorasan. It has also been found in Arabia Petra:a.

Turquoise takes a fine polish, and is much employed in jewellery, cut in low cabochon. It is much used in Oriental countries for ornamenting swords, daggers, cups, &c. This stone is very liable to lose its colour under the action of alkalies, such as, are contained in soap, or even by exposure to the light and the action of the air. The Mexicans had also a Turquoise which they used, as the Persians have always done, to ornament objects in clustered masses.

There is also a green variety of Turquoise. According to Mr. Eastwick, in the Persian Treasury is the finest turquoise in the world, three or four inches long and without a flaw.

PRECIOUS OPAL.

OPAL is a hydrate of silica, consisting of from 90 to 95 of silica, and 5 to 10 of water. There are several varieties. The most highly prized is the noble or precious opal, which exhibits a rich play of prismatic colours, which flash from minute fissures apparently striated with microscopic lines, due it may be to lamina, formed by incipient crystallization.

The colour is not due to any colouring matter, but  is in consequence of the diffraction of the light produced by these fine lines. When held between the eye and the light it appears of a pale red and wine-yellow tint, with a milky transparency. By reflected light it displays the most beautiful iridescent colours, green, yellow, red, blue, violet.

It is always cut with a convex surface. Fine stones are extremely rare, and seldom large. This variety is called the Harlequin opal. Golden opal is a term applied to that variety in which only one colour, an orange-yellow, is present. The common varieties do not exhibit the peculiar play of colours termed opalescence. They are sometimes made into pins, cane-heads, and other ornaments.

The finest opal of modern times was the Empress Josephine’s, entitled the ” Burning of Troy,” from the innumerable red flames blazing on its surface, the reverse being perfectly opaque. The largest opal known is in the Imperial Cabinet of Vienna. It is the size of a man’s fist, and weighs seventeen unces, but is full of Assures. Good specimens may be seen in the Townshend Collection, S.K.M.

The opal is found in Hungary, Mexico, and Honduras, and in small rounded pieces in sand, in Ceylon.

FIRE OPAL

Is a rich hyacinth-red variety of opal, from Mexico. It is also called Girasol and Sun opal. A fine specimen is in the Beresford Hope  Collection, S.K.M.

HYALITE.

A semi-transparent variety of opal, occurring in small reniform, botryoidal forms, resembling glass.

HYDROPHANE.

A variety of opal of a dull appearance, but which when immersed in water acquires all the opalescent tints of the precious opal. It is also of an opaque yellow, which when moistened becomes quite transparent. It adheres to the tongue. Its name is derived from vScop, “water”, and <f>a!,vw, “to appear”.

CACHOLONG.

A variety of opal, so called from its being found in great beauty on the borders of the River Cach, in Bucharia. It is nearly opaque, of a milky or bluish-white colour, dull exteriorly, but with a somewhat pearly lustre within. It is sometimes found associated with hydrophane.

MATRIX OF OPAL.

A porphyry containing minute veins of opal, running through it. Snuff-boxes and other ornaments are made of it.

ROCK CRYSTAL.

This colourless variety of vitreous quartz consists of pure silica crystallized. It is very common in. granite and other rocks and veins, in the shape of rock-crystal, presenting itself in six-sided prisms, terminating at one or both ends in six-sided shining pyramids. It scratches glass, and is harder than felspar, but is not so hard as topaz. It is found in various localities in almost every part of the globe; in the East Indies, Ceylon, Brazil, in several parts of England, Ireland, Scotland, where the crystals are called diamonds, such as Bristol diamonds, Isle of Wight diamonds, Irish diamonds. It is employed for ornamental purposes. In India it is cut into cups, vases, some elaborately carved.

AMETHYST.

Quartz, or rock crystal, coloured by a minute portion of iron and manganese. It is a transparent stone of a purple or violet colour. The finest amethysts are brought from India, Persia, Ceylon, Brazil, and Siberia. It is also found in Ireland. It is chiefly used for brooches and other ornamental purposes. The deep purple-coloured specimens are frequently called Oriental, by jewellers, to be distinguished from the true Oriental amethyst or violet sapphire.

YELLOW CRYSTAL.

This variety of quartz is sometimes called false topaz. The wine-coloured variety is called Cairngorm, after the name of the mountain in Invernessshire, where it is found. It is frequently used for ornamenting the handles of dirks, powder-horns, snuff-boxes, and other articles belonging to Highland costume. This yellow variety is found in every part of the world, in Brazil, Switzerland, Siberia, India.

The deep-coloured crystals found in Brazil are called cinnamon-stone, the French term being ” pierre de cannelle.” A fine kind is also found in Spain, of a dark yellowish-brown, which when heated becomes light-coloured, and assumes a fine orange tint.

BLUE CRYSTAL.

Water-worn pebbles of crystal, of a beautiful blue colour, are found in France in the stream of Rioupezzouliou, near Expilly, in Auvergne: they have been Galled saphirs de France, or saphirs de Puy-en-Velai.

ROSE QUARTZ.

A transparent variety of quartz of a rose-red or pink colour, probably produced by manganese. It is sometimes employed in jewellery. When cut and polished, and of good colour, it is sometimes sold for spinel. It is found in Rabenstein, in Bavaria, in a vein of manganese traversing granite, in France, in Finland, and also in Scotland and Ireland.

CITRINE.

A variety of crystal of a lemon-yellow colour.

SMOKY QUARTZ.

Crystals of quartz of a brown or smoke-coloured tint. It is also called morion.

IRIS.

The name applied by French jewellers to a variety of rock crystal, possessing the property of reflecting the prismatic colours by means of natural flaws in the interior of the stone. It may be produced artificially by dropping crystals suddenly into boiling water, or by heating and suddenly dropping it into cold water. The Empress Josephine possessed a suite of ornaments made of this stone.

EUCLASSE.

A name given by French lapidaries to a variety of rock crystal with rose-coloured cracks. These fissures are artificially produced by heating the crystal red-hot and then plunging it into a solution of purple of cassius, or carmine.

AVENTURINE.

A translucent variety of vitreous quartz of reddish colour, and containing minute yellow spangles of mica. It is found in India, Bohemia, Cape de Gata, in Spain, and in Siberia. Many ornamental articles are made of it. An artificial variety of it is made at Venice. It was discovered by chance {par avantura), a workman having accidentally let fall some brass filings into a pot of melted glass. The name has been derived from this.

A beautiful green variety is found in India, which is sometimes used for glyptic purposes. In the collection of Dr. Wise is a lingam of green avanturine, with the head of Siva carved on it