Читать книгу The Book of the Pearl. The history, art, science, and industry of the queen of gems онлайн

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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 nacral layers envelop the adjacent matter until it is entirely concealed within the pearl, its position being recognized only by the excrescence on one side, and, with continued increase in size, even this may be almost overcome.