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Emanuel gives the following qualifications, as necessary to a perfect pearl:
1. It must be perfectly round, or drop-shaped, seeming as if fashioned or turned into shape.
2. It must have a perfectly pure white color.
3. It must be slightly transparent.
4. It must be free from specks, spots, or blemish.
5. It must possess the peculiar luster characteristic of the gem. Pearls are sold by their weight in
grains,
rather than by carats, four grains equaling a carat. Seed pearls
weighing one grain are usually worth from one to three dollars each.
With the increase in size, however, the increase in price is rapid, a
two-grain pearl being worth, for instance, four times as much as a
one-grain pearl, a three-grain pearl nine times as much, and so on. The
largest pearls bring, like the largest diamonds, individual prices. The
pearl is, perhaps, the only gem that does not need to have its
beauties enhanced by cutting, nor can any polishing process improve its
surface. The favorite use of pearls is to string them in necklaces; but
they are also often set around other stones to heighten their effect,
or they are used alone in rings.
There
are numerous ways of producing imitation pearls, one of which,
invented many years ago by a French bead-maker named Jacquin, gives
remarkably accurate reproductions. The Jacquin pearls are made from an
easily fusible bluish glass, which is first drawn into tubes, and from
these, hollow globules of the desired size are blown. These are covered
on the inside with a solution of isinglass, and a substance called
essence of pearl, which is blown in warm, and spread over the interior
by rapid motion. When dry, the globules are filled with wax. The
essence of pearl, which constitutes the important feature of Jacquin's
process, consists of a silvery substance found beneath the scales of
the fish known as the bleak (Cyprinus alburnus). It is in the form of thin, irregular rhombic plates, and is obtained by washing the scales, one
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