We
read of an instance in an important paper treating of the jeweling
trade of Birmingham: "A few years since [the paper was written in 1866]
a small lot of shells was brought to Birmingham, which either from
ignorance or mistake had not been cleared of the pearls at the fishery.
A considerable number were found and sold, and one especially was sold
by the man who had bought the shell for working into buttons, for £40.
The purchaser, we believe, resold the same for a profit of f 160; and
we have heard that it was afterward held in Paris for sale at £800."
A choice gem which was found in New York, in October, 1905, in an Australian shell, sold finally for $1200.
The
intrusion and continued presence of grains of sand or similar material
between the mantle and the shell causes the formation of nacre over the
foreign body, resulting in a chicot (blister pearl), or possibly a quarter or a half-pearl. The growth of a chicot sometimes
results from the mollusk covering a choice pearl which has become
loosened from the soft tissues and adheres to the shell, as above
cited. Hence, it is sometimes desirable to break a chicot to
secure its more valuable inclosure. In the account of his interesting
pearling experiences on the Australian coast, Henry Taunton states:
"During the first season's shelling at Roebuck Bay, we came across an
old worm-eaten shell containing a large blister, which was removed in
the usual manner by punching a ring of minute holes around its base; a
slight tap was then sufficient to detach it. For many weeks it was
untouched, no one caring to risk opening it, for if filled with black
ooze, which is frequently the case, it would be of little value. At
last, baffled in his attempt to solve the problem, and emboldened by an
overdose of 'square face,' the skipper gave it a smart blow with a
hammer, which cracked it open, and out rolled a huge pearl, nearly
perfect, and weighing eighty grains. A few specks and discolorations
were removed by a skilful 'pearl-faker,' and it was sold in London for
fisoo."1
Blister
pearls are also caused by the defensive or protective action of the
mollusk in resisting the intrusion of some animal, as a boring sponge
or a burrowing worm, which has begun to penetrate the outer layers of
the shell. This stimulation causes the mollusk to pile nacreous
material upon the spot, thus making a substantial mound closely
resembling a segment of a large pearl. This walling-out of intruders is
not the result of intelligent forethought or of instinct, analogous to
the repairing of a damaged web by a spider, or the retunneling of a
collapsed gallery by ants ; it is a pathological rather than an
intelligent action.
When the nucleus of a pearl is large and very irregular, it necessarily
1 Taunton, "Australind," London, 1903, p. 224.
