Imperfections which can be hidden by the setting decrease the price twenty to thirty per cent., and there is about the same difference between button and round pearls, according to the size of the plane. The difference is still greater in the larger sizes. A yellow color reduces the value in the market from fifteen to fifty per cent. according to the depth and quality of the tint. The so-called blue pearls, which are of a dark leaden white, are worth about half as much as ordinary white, and about one-third the price of fine white Indians. These blue pearls must not be confounded with the deep gray, slate, or black pearls, included in the general term black pearls, as the latter frequently command fancy prices.
Salt-water pearls taken from the smaller varieties of the avicula of some seas, though of the same grade in the qualities of color, luster and shape, are nevertheless worth less than Indian pearls, because they lack a certain quality of texture which the latter, together with those of some other waters, possess to an eminent degree.
American fresh-water pearls have been and are lower in price than Orientals. They have however commanded much better prices of late than formerly and are increasing in value. At present they bring about one-third less than corresponding qualities from the seas. There is a greater difference in the price of baroques. Fine Venezuelan baroques from a half to seven or eight grains are worth now thirty-five to fifty cents base.
Some of these when mounted appear like round or pear-shape pearls and are in good demand. Larger pieces can rarely be made to appear other than baroque and do not therefore command as good figures. They seldom bring more than five dollars per grain flat, in sizes from ten to twenty grains. Fresh-water pearls likewise fetch better prices reckoned by the multiple in the smaller sizes, though they are usually quoted by the grain flat at five to twenty-five cents under ten grains, and twenty-five cents to three dollars per grain in larger sizes.
Iridescent, finely tinted, very lustrous, strawberry, and rose baroques of large size, are worth five dollars per grain and very exceptional pieces bring even more. Slugs, or ordinary baroques, are sold all the way from six dollars an ounce to ten cents per grain. Good wing-pearls can be bought at one to five cents per grain; small wings and rejections are sold by the ounce.
Perfectly round fresh-water pearls of good quality and even skin are rare and prices are advancing steadily. Good buttons have advanced fully twenty-five per cent. in the last year. Fine fancies such as were found at one time in the Sugar River, Wisconsin, since the fisheries there have been exhausted, are scarce and high.
The low prices paid by button manufacturers for mussel shells for the mother-of-pearl in them during the past year, has been one of the chief factors in reducing the quantity of pearls found and the consequent increase of price. It seldom pays the fisher to gather mussels for pearls only; it is the steady returns from the sale of the shells which ensures an adequate reward for his labors. Shells that once brought twenty dollars per ton fell during the early part of 1905 to a third of that amount and later went as low as two dollars and a half. They are now going up again.
Many pearls are seriously injured by the practice of fishers who rely upon the sale of the shells for their returns, of throwing the mussels into vats of hot water to open them. The pearls released from the shells fall to the bottom and getting too near the hot iron are killed, which means that the luster is partially or wholly destroyed.
Dredging is now quite common and is doing much to deplete the mussel-beds of the west. When one bed is completely divested of shells, the clammer moves on to another and repeats the process, so that the supply of fresh-water pearls is coming to depend on the constant discovery of new mussel-beds. Unless legislation regulates the industry the American supply will soon cease.