Pearls
are in a sense the purest of all gems, since they alone require no
polishing or cutting at the hands of workmen, but are found in nature
in their most finished form of perfection. They have been known and
prized since long before the Christian era. They are said to have been
known in China four thousand years ago. The gems occur more or less
extensively in almost every country where oysters or mussels are
found. The pearls of the greatest value are the Orientals, found
in the Indian and Pacific oceans. The famous fisheries of Ceylon
furnish a large percentage of fine pearls, although the gems found
there are seldom of large size. The Ceylon oyster is comparatively
small, only about four inches in length and with a thin shell, while
the oyster of the South Seas, Australia, and the Philippines is very
large and thick. From these large pearl oysters comes the beautiful Mother of Pearl much used in commerce.
The fresh-water pearls are found in streams,