Meyer D. Rothschild

“ Although a finely developed diamond, ruby, or other crystal is sometimes found and used for jewelry, the beauty of a precious stone generally remains hidden within a rough and unsightly exterior until the lapidary’s art reveals the gem. ”

“ Harder than the tourmaline, turquois, or opal, as hard as the chrysolite, and nearly as hard as the garnet or emerald, there is no reason why the crystallized varieties, such as amethyst, cairngorm, false topaz, chrysoprase, and even the cat’s-eye and finer onyxes, should not be classed among the precious stones.
Some more plentiful and less beautiful varieties of quartz are not valuable, and they take the same position in the quartz family that the huge imperfect crystals do in the beryl group. ”

“ The various other colored sapphires, such as yellow or Oriental topaz, light green or Oriental aquamarine, greenish-yellow or Oriental chrysolite, and aurora-red or Oriental hyacinth, are all valuable as gem [Pg 45] stones when they are pure, well cut, and have pronounced colors—in fact, the name Oriental is given to distinguish the corundums from the less valuable minerals of the same colors which they resemble, but which they greatly surpass in beauty and value because of their brilliancy and superior hardness. ”

“ To draw such a line is hardly possible, as neither hardness, rareness, nor value would be a positive test—some of the hard stones, like zircon and almandines being less valuable than the softer opal, while the diamond, one of the most plentiful of precious stones, is at the same time, one of the most valuable. ”

“ The red sapphire or ruby is the most valuable of the corundum family, and when found of a good color, pure and brilliant, and in sizes of one carat and larger, it is much more valuable than a fine diamond of the same size. ”

“ The diamond is a non-conductor of electricity, but acquires positive electricity when rubbed, and retains it for half an hour. After being exposed to the solar rays, the diamond presents a distinct phosphorescence in the dark. It possesses single refraction, but belongs to those bodies which reflect light most strongly, and its magnifying power is much greater than that of glass; it does not polarize light; its lustre is adamantine, and specific gravity 3.5 to 3.6. The diamond is the hardest of all known minerals, ranking No. 10 in Moh’s scale of hardness. ”

“ The garnet and topaz are easily scratched by the ruby, the hyacinth is [Pg 43] heavier, and quartz and tourmaline lighter than the ruby. Some so-called reconstructed rubies, recently offered for sale, are of a very fine color, and closely resemble the Oriental gems.
The hardness and specific gravity are the same, but they differ in one very important point, namely: they lack the brilliancy of the true ruby. In addition to this lack of fire, a microscopical test discloses formations which will distinguish the manufactured from the natural stone. ”

“ The Oriental emerald or green sapphire does not approach the beryl or true emerald in depth of color, but because of its superior hardness and brilliancy, added to its extreme rarity, it is the most valuable of green gems. The Oriental amethyst or purple sapphire sometimes reflects a red color by artificial light, and is valued highly as a gem stone; the common amethyst is softer, less brilliant, and loses by artificial light. ”

“ When a stone is examined by means of the dichroiscope, it will show two images of the same hue, or of different hues, these square images (fig. 1, A) forming a right angle and being more distinct when viewed from one part of the stone than from another.
When the images are identical in color, the specimen may be a diamond, garnet, spinel, or glass. Should a red or ruby spinel approach the ruby in color, a quick and satisfactory test can be made with the dichroiscope, as the spinel will show two images of one color, while the ruby will show one image of aurora red and one of carmine red. ”

“ The emerald or green beryl is one of the most highly prized of the gem stones. Its magnificent color has rightly been compared to the color of the fresh grass in spring, and in brilliancy this stone far exceeds all other green gems, excepting only the very rare green corundum or green sapphire. ”

“ Quartz crystallizes in the rhombohedral system, and many varieties are found massive and compact. The cleavage is indistinct but can sometimes be found by plunging a heated crystal into cold water. The hardness of quartz is 7; specific gravity 2.5 to 2.8, the purest kinds being 2.65; the lustre is vitreous to resinous, and fracture conchoidal.
Quartz is tough, brittle, and feels cold; it becomes positively electric by rubbing, shows phosphorescence in the dark, and gives sparks if struck with another piece of quartz or with steel. ”

“ The emerald is said to be very soft when first withdrawn from the mine, but it hardens by exposure to the air.
A perfect emerald of fair size is a rarity, so that the saying “an emerald without a flaw” has passed into a proverb.
This stone is so light, compared to a diamond or sapphire, that a carat emerald will be very much larger than either of the above stones.
The emerald is composed of: [Pg 52]
The vivid green color of the emerald is supposed to come from the oxide of chrome, as the other beryls do not contain chrome. ”

“ The white spinel, which is seldom found, is sometimes confounded with the diamond, having the same specific gravity and single refraction, but as it lacks the fire and is easily scratched by the diamond, the danger of mistaking one for the other is slight. ”

“ Cyanite is colorless to bluish-white, sky-blue, berlin blue, yellowish- and reddish-white, gray, and green.
The hardness is 5 to 7, specific gravity 3.45 to 3.70, lustre vitreous and pearly; it is infusible before the blow-pipe, but fuses with borax; is not attacked by acids, and is composed of:
Cyanite is found in Switzerland, the Tyrol, Styria, Carinthia, Bohemia, Norway, Finland, France, South America, Scotland, Ireland, Siberia, the East Indies, and the United States. ”

“ Crystals have also been found in the United States.
The amorphous or carbon diamond is found only in Brazil. The pebbles or [Pg 38] masses are opaque, steel-gray to black in color, and sometimes weigh 1,000 carats.
This carbonate is principally used to point rock-drills and for other engineering purposes. The coarse variety of crystallized diamonds is called bort, and as this is unfitted for gem purposes because of imperfections, it is ground into powder and used for cutting and drilling precious stones.
White sapphires, white zircons, white topaz, and rock-crystal sometimes pass for diamonds. ”

“ Goutte d’eau or colorless topaz, sometimes called “slaves diamond,” Siberian or bluish-white, Brazilian or golden to reddish-yellow, Saxony or pale-wine yellow, Brazilian ruby or pink, Brazilian sapphire or light blue, and aquamarine or greenish, are the various commercial names for topaz.
Most of the Brazilian rubies or pink topazes are produced by heating the reddish or dark-yellow variety, either in a crucible or by [Pg 86] enveloping the stone in German tinder and setting fire to the tinder. If heated too much, the stone is apt to become colorless, and if suddenly cooled it may crack. ”

“ Mineral turquoises are also found in New Mexico, Arizona, and Nevada, but not of sufficient size or sufficiently good color to make gem stones, although they are prized for collections. Specimens are also found in Burmah, Khorassan, Thibet, China, Silesia, Saxony, and on the Isthmus of Suez. The stones from these places have, as a rule, but little value, as the color fades or turns green from exposure to the light. Of late however, some very good turquoises have come from Egypt. The color of a faded Persian turquois can sometimes be restored by simply repolishing the stone. ”

“ According to modern scientific investigation, the formation of the pearl does not seem to be the result of healthy natural causes, but comes from the efforts of the oyster to rid itself of some foreign substance, like a grain of sand, a bit of shell or vegetation, or some unwelcome visitor in the shape of a small water insect. ”

“ The hardness of the turquois is 6., specific gravity 2.6 to 2.8, lustre waxy, and condition opaque to slightly translucent. [Pg 61]
Before the reducing flame of the blow-pipe, the turquois does not melt, but becomes brown and colors the flame green. With borax and salts of phosphorus the turquois melts to a clear glass, while it is also soluble in hydrochloric acid. Oriental or mineral turquois is composed of:
The best color is a clear deep sky-blue, and in the true turquois this color improves by artificial light ”

“ When one or more layers are of carnelian or sard, the stone is called sard-onyx. Sard is a rich brown color inclining to red, and when held against the light shows a red hue.
Onyx and sard-onyx are often artificially improved by boiling the stones in honey, oil, or sugar water, and then in sulphuric acid. The acid carbonizes the sugar or oil which the stone has absorbed and gives it a deeper color. ”

“ Neither can price be taken as a complete test, because fashion makes a turquois, an opal, or an emerald much more valuable at one time than at another. All precious minerals used for ornamental purposes, from the diamond to quartz, or chalcedony, may properly be termed precious stones.
[Pg 10]
Physical Characters. CRYSTALLIZATION.
Precious stones are found either in crystallized or amorphous conditions. The forms of crystallization are:
Most precious stones crystallize, but the specimens that have the crystallization clearly defined are seldom found. ”

“ The lustre is highly metallic, with slight iridescence.
The island of Elba, France, Switzerland, Italy, Norway, Sweden, Bohemia, England, Brazil, Chili, Canada, Spain, and the United States are places where hematite is found. The Germans call this mineral “blood-stone,” and it is also known as specular iron ore and iron glance.
Obsidian.
Obsidian, or volcanic glass, does not occupy a high position as a gem [Pg 126] or as an ornamental stone, but its antiquity and occasional use among the agates and semi-precious stones will justify its mention. ”

“ A perfect ruby is rarely met with, and a stone possessing brilliancy and the true color, even if slightly defective, is considered more valuable than an absolutely perfect ruby of an inferior color.
Rubies are found in Siam, Ceylon, Burmah, Brazil, Hindustan, Borneo, Sumatra, Australia, France, and Germany. ”

“ The diamond is one of the most precious minerals, and yet it consists of pure carbon, the most common substance that is known, a substance that is present in all animal and vegetable bodies and in the larger number of minerals. ”

“ Spinels crystallize in octahedrons and their modifications, the fracture is conchoidal, specific gravity 3.5 to 3.6, and hardness No. 8 in Moh’s scale; only the diamond, corundum and chrysoberyl will scratch the spinel.
Its refraction is single, the lustre highly vitreous, and it does not easily acquire electricity.
Acids do not attack the spinel, nor has the blow-pipe any effect on this mineral, except to change the red to a brownish or colorless state, but the original color returns when the stone cools. [Pg 48]
Flawed or imperfect stones are liable to crack or split if heated too much. ”

“ Although choice sapphires are rare, a much greater quantity of good and large stones are to be had than of rubies, and therefore the price of a large sapphire does not advance in the same proportion as the price of a large ruby. ”

“ Green tourmaline sometimes passes for the emerald, but it is somewhat softer and considerably heavier.
Olivines or chrysolites, if of a fine green color, sometimes resemble the emerald, but they are much heavier than the emerald and have a fatty lustre. Green spinels are heavier and harder than emeralds. ”

“ Thus it will be seen that corundum is composed almost wholly of alumina,—one of the constituents of common clay, which, when colored by traces of metallic oxides, chrome, etc., produces a greater variety of precious stones of a high rank than any other mineral. ”

“ Felspar. Easily scratches glass; is attacked by a file, and gives some sparks against steel.
No. 7. Quartz. Quite hard; is only slightly attacked by file; gives sparks readily against steel.
No. 8. Topaz. Very hard; is not attacked by a file.
No. 9. Sapphire. Hardest of all minerals but the diamond; attacks all other minerals.
No. 10. Diamond. Attacks all minerals; is not attacked by any.
To find the hardness of a stone, begin to test with the softest mineral, so that when the number is reached which will scratch the stone, there has been no injury to the specimen under examination. ”

“ As there are so many other beautiful and rare gems which nature yields to man, and which are worthy of the jewelers’ art, the author trusts that his book will awaken a new interest in the fascinating study of mineralogy as applied to precious stones, and that at some future day he may feel encouraged to enlarge upon this treatise. ”

“ During the conquest of Peru by the Spaniards, many very fine emeralds were destroyed by the invaders, who tested them by grinding and pounding, and concluded that the emeralds were worthless, because they were not as hard as the diamonds or sapphires. ”

“ Some of the oysters die, but most of them are found to have been actively at work covering the little pellets or metal figures with nacre, and while no strictly first-class pearls are formed in this way, many curious little pearl figures or gods are made and sold to the curious or devout. ”

“ This mineral is a melted lava, and consists of silex, alumina, and a little potassa, soda, and oxide of iron. Obsidian is 6 to 7 in hardness, has a specific gravity of 2.25 to 2.8, is sometimes transparent but mostly translucent to opaque, and is vitreous to metallic in lustre. It is brittle and not easily attacked by acids. ”

“ This many-colored mineral, composed of nearly pure alumina, produces gems which in some cases are more valuable even than diamonds. The ruby, sapphire, Oriental emerald, Oriental topaz, Oriental amethyst, Oriental aquamarine, Oriental chrysolite, Oriental hyacinth, star ruby, star sapphire, star topaz, and ruby and sapphire cat’s-eyes are all corundums of different colors. The ruby is a red sapphire, and the Oriental topaz a yellow sapphire, while the Oriental emerald is a green sapphire, etc., etc. ”