Pearls and Conch Shell
Among univalves, the most prominent pearl-producer is probably the common conch or great conch (Strombus gigas) of the West Indies and the Florida coast, which secretes beautiful pink pearls of considerable value.
This is one of the largest of the univalve shells, some individuals measuring twelve inches in length, and weighing five or six pounds. The graceful curves and the delicate tints of lovely pink color make it exceedingly attractive. The conch abounds in the waters of the West Indies, especially here in the Bahamas, a group of more than four hundred islands off the Florida coast, where many thousands are annually taken for the shell, which forms quite an article of commerce. The flesh is esteemed as food and is also used for bait; and it is particularly in preparing for these purposes that the pearls are found, as no established fisheries exist for the pearls alone.
Those who gather these shells have been called, "Conchs".
Near the shores, where they formerly abounded, a few conchs are yet picked up by wading fishermen. In waters of medium depth they are secured either by diving or by means of a long pole with a hook at the end. In great depths, the mollusks are located by means of a water glass similar to the type employed in the Red Sea or among the South Sea Islands.
The animal is readily removed from the shell after crushing the tip end of the spire where the large muscle is attached. The flesh forms an important article of food to the fishermen and to the residents of the outlying islands. It is said that a "Conch" can make a visit to Nassau of a week or ten days, and subsist almost entirely on this dried meat, with which he fills his pockets on starting. A large demand exists for the beautiful shells for ornamenting flower-beds, garden-walks, etc. Many of them are burned into lime for building purposes. Formerly several hundred thousand shells were exported annually to England for use in porcelain manufacture.
The pearls are generally found embedded in the flesh of the mollusk; quite often they are in a sac or cyst with an external opening form which they are sometimes dislodged by the muscular movement of the animal. The yield is small, a thousand shells in many cases yielding only a very small number of seed-pearls or perhaps none at all. Most of them are oval, commonly somewhat elongated. The usual size is about one grain in weight, but some of them weigh over twenty, and a very few exceed fifty grains each.
These pearls are generally of a deep pink color, shading toward whitish pink at each end. While this is the usual color, yellow, white, red, and even brown conch pearls are occasionally obtained; these are not so highly prized as the pink ones.
Conch pearls present a peculiar wavy appearance and a sheen somewhat like watered silk, a result of the reflections produced by the fibrous stellated structure. While many are beautifully lustrous, they are commonly deficient in orient, and the color is somewhat evanescent.
Most of the Bahama conch fishermen sell their catch of pearls at Nassau.
The value of conch pearls is as variable as their form, color, and size, and they are sold by the fishermen for a variety of prices which range quite high for large ones with exceptional form, color and luster.
There are two important materials that have occasionally been sold and mistaken for the conch pearl. First, the pale Italian, Japanese, or West Indian coral, with a color very closely approaching that of the pearl. By means of a lens it can readily be seen that the coral is in layers, and does not possess the concentric structure of the pearl, or the peculiar interwoven structure, with its characteristic sheen, so frequent in a conch pink pearl.
Secondly, the pink conch shell in which the pearl itself is found; this is frequently cut to imitate the pearl and sold as such in the West Indies and elsewhere. This can also be detected by the fact that the layers are almost horizontal and the structure is not concentric or interwoven, as it is in the conch pearl, while the luster is more like that of the shell than that of the pearly nacre.
Streeter related that many years ago an ingenious American turned out some bits of conch shell into the shape of pearls and placed them in the conch shells. A slight secretion formed over them, but it was not the true pearly secretion, and the layer was very thin, so that the deception was easily detected.
A yellow conch shell is called Cassis madagascarensis.
Conch pearls contained in the famous Hope Pearl Collection include an oval pearl, pink in general color and somewhat whitish at the ends, weighing eighty-two and one fourth grains and another conch pearl, seventy-seven and one half grains, button shaped, yellowish-white with a slight shade of pink.
Thanks to Kari for some of the above photos, Kunz and Stevenson for this information from their 1908 book.