56 THE BOOK OF THE PEARL
stances
; consequently they originate only in the soft parts of the mol-lusk
and not by the fixation of some nucleus to the interior surface of the
shell.
The
perfectly spherical pearls range in weight from a small fraction of a
grain to three hundred grains or more, but it is very, very rare that
one of choice luster weighs more than one hundred grains. The largest
of which we have any specific information was that among the French
crown jewels as early as the time of Napoleon, an egg-shaped pearl,
weighing $27 grains. The largest pearl known to Pliny in the first century a.D. weighed
"half a Roman ounce and one scruple over," or 234-1/2 grains Troy.
These very large ones, weighing in excess of one hundred grains, are
called "paragons." The small pearls—weighing less than half a grain
each—are known as "seed-pearls." The very small ones, weighing less
than 1/25 of a grain, are called "dust-pearls." These are too small to
be of economic value as ornaments.
Slight departures from the perfect sphere, result in egg shapes,
pear shapes, drop shapes, pendeloque, button shapes, etc. Some of these
are valued quite as highly at the present time as the spherical pearls,
and many of the most highly prized pearls in the world are of other
than spherical form. Indeed, pearls of this kind are found of larger
size than the perfectly round pearls. The egg-shaped pearl,1
called "la Régente,"—one of the French crown jewels sold in May, 1887—
weighed, as stated above, 337 grains. The great pear pearl described by
Tavernier—"the largest ever discovered"—weighed about 500 grains. A
button pearl received from Panama in 1906 weighed 216 grains.
Wider
departures from the spherical form result in cylindrical, conical,
top-shaped, etc. Some pearls present the appearance of having been
turned in a lathe with intricate tooling. Remarkable examples of these
"turned pearls" have been found, competing in their circular perfection
with the best work of a jeweler's lathe.
Many
standard varieties of non-spherical, but normally shaped pearls, are
recognized by the fishermen and the jewelers. For instance, in the
nomenclature of the American fishermen, bouton, or button
pearls are divided into "haystacks" and "turtle-backs," according to
the height of the projection. Also, certain imperfections result in
distinguishing names: "bird's-eye" refers to a pearl having a little
imperfection on the best surface; "ring-arounds" have a dark or
discolored ring about them; and "strawberries" have numerous minute
projections on the surface.
During
its growth, a spherical pearl may come in contact with a foreign body,
such as grit or a vegetable film, and the additional nacrai layers
envelop the adjacent matter until it is entirely concealed within
1 Now in the French crown brooch in the possession of the Princess Youssoupoff of Russia.
