IMITATION AND DOCTORED PEARLS
In common with all other precious things, pearls have been long imitated. The early method of making imitation or "mock-pearls" as they were called, was to cut them out of the mother-of-pearl and polish them. Another crude way was to make solid beads of glass containing various ingredients which gave them a slight similarity to the nacreous luster of the pearl. Beads of gypsum or alabaster were soaked in oil and coated with wax. The scales of the bleak fish dissolved in liquid ammonia or vinegar, was also used for covering beads, the solution imparting a somewhat pearly appearance.
To coat one thousand ounces of glass beads, a French manufacturer used three ounces of fish-scales, one ounce white wax, one ounce pulverized alabaster and half an ounce fine parchment glue. Another made beads of opal glass which he covered with several layers of isinglass; over this was laid another coating of a mixture of spirits of turpentine and copal, and a fat oil to exclude moisture from the isinglass, following it with a thin layer of tinted enamel to give resemblance to the orient of the pearl.
Some claimed that the best artificial pearls were made from pulverized pearls. Seed pearls or valueless baroques were ground to a fine powder, soaked in lemon-juice or vinegar and mixed with gum tragacanth. The paste after being shaped and partially dried, was then enclosed in a loaf and baked in an oven. The luster was obtained by a final coating of fish-scale solution. A lighter and better imitation was made by blowing hollow glass beads. The inside surface was covered with a preparation from the fish-scales, after which the bead was filled with wax. This method continues in use to-day.
The fish-scale solution used is a guanine, the mucus which lubricates the scales of the bleak fish (alburnus lucidus). The white scales of the fish are carefully scraped into a horse-hair sieve over a shallow tub of fresh water. The first water is thrown away. The scales are then washed and pressed. The mucus sinks to the bottom and is gathered as an oily mass, very brilliant and bluish-white. This is packed with ammonia in tin boxes and sealed for shipment. It takes about 20,000 fish to make one pound of the mucus.
A cheap imitation pearl is made of opal glass, a bluish-white milky appearing material, to which a pearly effect is given by treating it with fluoric acid. Imitation black pearls are made from hematite, but as they require careful finishing to hide the metallic luster and are much heavier than pearls, they are seldom used.
The Chinese and Japanese have been much more ingenious in their methods and have long produced, with enforced aid from the animal, imitations which are in part real pearl. The former insert in the Chinese pearl-mussel (anodonta herculea) small figures of Buddha upon which the fish proceeds to deposit its nacre. When they are coated, which occurs in from one to two or three years, the pearly figures are extracted and sold to the devout.
The Japanese do more. They attempt to produce a marketable gem and have so far succeeded that a considerable number have been sold of late in the United States and in many cases the public buy them not knowing that they are an artificial production. The base upon which the nacre is deposited appears to be composed of a substance resembling porcelain shaped like a low dome hollowed out on the under side and having a hole in the centre of the cavity.
As there is no nacre on the under side, it must, when the button is placed in the mussel, be thereby protected from the action of the fish except at the edges where the nacreous deposit probably joins it to the shell but in such a manner that it can be easily detached. The pearl covered button is then fitted to a piece of polished mother-of-pearl of the same exterior size and shape and the two are neatly joined, forming a double low domed piece of pearl on one side, and mother-of-pearl on the other. These Japanese pearls as they are called, when mounted in a setting constructed to hide the under side, have the appearance of imperfect spheres of natural pearl.
The beds where the culture of these artificial pearls is carried on, are situated in the Bay of Ago, a few miles south of the Temple of Ise, in central Japan on the Pacific side. It is a quiet piece of water, in a coast broken by numerous inlets and coves. A little north of the centre of the bay is a small island called Tadoko where the necessary buildings and the men connected with the industry are. Around the island and near it, about 1,000 acres of sea bottom are leased and used for the pearl oyster cultivation. The water is about five to seven fathoms deep.
The oyster used is the one common to the waters of Japan, the Avicula martensii Dunker. In May and June, stones weighing six to eight pounds are scattered over the bottom of the sheltered shallows which run up into the land, where the spat is collected. The breeding season is in July to August and in the latter month very tiny shells attached to the stones by the byssus may be seen already.
The number increases as the season advances until in November, in order to protect the young fish from the approaching winter cold, the stones lying in very shallow water are removed with the adhering oysters to deeper water—over six feet. After three years the oysters are taken out and the nuclei of the culture pearl inserted. This done, they are spread over the sea bottom, about one to every square foot and left undisturbed for four years. They are then taken out and opened and both the culture pearls and whatever natural pearls there may be, are harvested. At present, upwards of a quarter of a million oysters are treated annually.
Experiments are being made constantly, in the United States and Europe, to improve upon the hollow glass bead lined with fish-scale but so far without success. The finest of these imitate the natural pearl very well and if finely mounted similar to the genuine, will deceive many while worn. Closer observation will reveal the glassy shine of the surface and it will be found under the loup to contain numerous small holes. The specific gravity is also less.
One finds occasionally in lots, a mock-pearl which has been cut and polished from the mother-of-pearl, but imitations of this character are scarce and find no place in the market. The few made are found usually in parcels of fresh-water pearls and are put there by unscrupulous dealers, as also are hematite balls and even buckshot, to be sold with the lot by weight as genuine pearls.
Since the price of pearls has advanced so rapidly, much ingenuity has been shown in the improvement of poor pearls. Button pearls grown to the shell are broken out and the under or flat side carefully scraped and smoothed to hide the irregular lines of juncture between the pearl and the shell. Protuberances on the surface of round pearls are scraped off and the broken skin edges smoothed down so as to be unnoticeable to the naked eye.
In a like manner chalky rings and spots are toned down. Surface cracks are filled by soaking the pearls in a solution and if the pearl has been pierced, interior cracks can also be rendered unobservable. A serious objection to pierced pearls arises from the ease with which interior defects can be doctored where the skin is pierced and a boring made through the nacreous layers. Not only are cracks made to disappear, but coloring matter can be introduced between the skins. A white pearl of very poor color can by such means be changed temporarily into a black pearl which will command a fancy price. This illegitimate doctoring of pearls, whereby defects are hidden and a fictitious appearance of quality imparted to last long enough to make sales at exorbitant prices, should not be confounded with the legitimate improvement of pearls which is now growing to be an industry of some importance. Experts are now able by careful manipulation to restore to some extent the luster which has been lost by wear or age.
Formerly this was done by skinning the pearl, i.e., removing the outer skin by peeling it carefully off with the edge of a sharp knife, an unsatisfactory method at best, as the under skin may not be good and if all the outer skin is not taken off, the broken edges of the layers composing the skin, mar the luster and color when the pearl is worn. Few also succeed in removing a skin without scratching the new one disclosed by its removal.
Pearls having a decidedly bad outer skin with a good one under it, can only be materially improved by removing the bad skin, but owing to the liability of finding equally bad imperfections underneath, or irregularities which would necessitate the removal of several skins with a consequent loss of size and weight, pearls with minor imperfections or lack of luster are now slowly rubbed between the fingers, the abrasion being assisted by various substances which differ with the judgment and experience of the operator, the preparation being in all cases kept secret by the expert using it. Many fine pearls which have lost their pristine luster are now considerably improved by this method, and without the dangers involved and the necessary loss of weight, consequent on peeling.
Large numbers of poor or imperfect pearls are scraped or otherwise doctored by the traders and speculators at the fisheries. These men acquire such pearls at a slight cost, and by various methods fix them so that by mixing them in lots with good pearls, they often make large profits. They also mix in many cracked pearls. This is done more often at Margarita and the other Venezuelan fisheries where the proportion of cracked pearls is greater than in the Indian and South Sea fisheries.
The skins of a pearl may also be removed by the application of weak acids, but this method requires careful and expert handling or the acid will act irregularly and leave the surface, if improved in luster, uneven and pitted.
Few important fresh-water baroques and irregular pearls leave the west without receiving the attention of the speculators through whose hands they pass, and the scraping is often very roughly done. Rough and discolored projections are broken or filed off and then scraped over with a knife edge. While fresh, the broken skin edges left thus will often pass unnoticed by a careless buyer, but they become discolored and dead later. Unless one buys of a dealer in whom implicit confidence may be placed, not alone for honesty but for his knowledge of pearls, it is better to examine all pearls under a glass before purchasing.
As many persons both in the trade and out of it, are not sufficiently familiar with pearls to be quite sure of their ability to detect the genuine from fine imitations, the following points of difference will be of service. All imitation pearls made of some solid material are heavier than the genuine and lack the pearly characteristics of the fine imitations even. If made of solid glass without acid finish, they are shiny and too poor to require a second consideration, if acid finished they have a "ground-glass" appearance which is unmistakable. If made of other material of a vitreous nature, they are heavier than pearls, dull in luster or without luster, dark in color and unmistakably lacking in pearly characteristics. The only dangerous imitations are the Japan culture pearls and the hollow, glass bead-pearls. The former may always be recognized by the mother-of-pearl back, the latter by various signs.
All these hollow glass beads, have one or two holes. They are coated on the inside with fish-scale solution and filled with wax. Some are treated with acid or sand-blasted to tone down the shiny, glassy appearing surface, and to hide the blow-holes in the glass. The effect is quite pearly, but the color is somewhat darker and they show some iridescence. Without the surface treatment they are more shiny and under the loup one will discover the small blow-holes peculiar to surfaces which have been molten.
The rims of the holes have a smooth, rounded, congealed appearance, whereas holes in pearls have a rough, square, chalky edge. On looking diagonally into the hole of a glass bead, the glass will appear as a dark ring against the wax filling, and where there are two holes, one will almost invariably have a ring in the glass, a short distance from and around it. The surface over the ring is smooth, though it looks as if it were ridged; the ring is in the glass, not on it.
These hollow-blown glass pearls are lighter than the real pearls also. There is one never failing test however which discovers even the best of these most dangerous imitations. Drop a small spot of ink from the point of a pen upon one, and hold it between the eye and the light, when two spots will appear, the one nearest to the eye being a reflection from the inner wall of the glass resting against the wax, of the actual ink spot on the surface. The duplicate spot will be lighter in color than the original. On a real pearl there would be no such reflection, nor would it appear on a solid bead imitation, but as before stated, the weight of the latter betrays them, as they are heavier than the real, nor do they look as pearly, and on holding them between the eye and light they do not show the translucency at the edge of the circumference peculiar in a more or less degree, to the gem.