Pearls are not as durable as gold, bronze, crystal gems or even glass. They are relatively delicate organic gems produced by living creatures. Do best in relatively, consistent medium humidity.
They are created by mollusks living in lakes, rivers and streams in great oceans as well as bays, inlets, lagoons and atolls.
To think it has been made by a little sea animal for us to look at and enjoy. If you think of all they go through to be formed, they are a miracle of creation-they truly are magical. Most people are not aware of how they are formed. It’s creation starts in a tiny mollusk. An irritant of some type, usually a miniscule snail, mud, shell or a tiny parasitic worm accidentally gets into the mollusk. This causes the mollusk to secrete nacre (pronounced, Nay-ker). This is a protective coating of this pearly substance. Most mollusks go through their life span never producing a pearl. The production of a pearl then is a miracle of nature. And a pearl that is perfectly round is very rare indeed. Moreover, today most pearls are cultured. This is because most of the natural waters that the mollusks feed in have been destroyed by pollution, eg. the Persian Gulf. Cultured pearls are helped in their creation by man, and usually the irritant is intentionally placed by man.
In saltwater pearls usually originate from the insertion of a shell bead nucleus along with a bit mollusk mantle tissue (a membranous tissue that secretes nacre and lines the inner shell surface of mollusks) into a mollusk. And in freshwater pearls, pieces of mantle are placed into a mussel or oyster. In both cases, the shape and size of the resulting pearls depends to a large degree on the shape and size of the implanted irritant. Because the mollusk is so small (Japanese oysters grow to only about 10 centimetres or 4” in diameter), the size of the pearl can be a substantial irritation indeed. Many times its size can be the cause of the mollusk’s premature death. In fact, many cultured pearl oysters die when a nucleus is inserted or when pearls are later removed. As you can see, the creation of a pearl is a miracle of nature and would not exist if not for the tiny mollusk.
What is a pearl?
Pearls are the only gemstones that are formed within living creatures, and due to this, no two can ever be exactly alike.
If the mollusk deposits nacre on its shell, that product, however shaped, is mother-of-pearl. If the mollusk deposits nacre on an object encased in its flesh, the product, however shaped, is pearl. A pearl can form naturally or when a mollusk coats an implanted nucleus. Only pearls that grow in the mantle or body deserve to be called simply “pearls”. Half pearls, or blister-pearls, traditionally known as pearls, require their own definition. They form naturally when a piece of debris sticks to the inside of a shell or a parasite bores through form the outside. Either way, the mollusk coats the irritant. If a natural object is a bump or a slight dome, it is mother-of-pearl. If it is half a sphere or more, it should be called a half-pearl, or a blister-pearl.
Mabes are the principal commercial objects produced on shells. While an oyster is out of the water for nucleation, small plastic half-domes are glued to the surfaces inside its shell. Back in the ocean, the oyster coats both the nucleus and the plastic domes with nacre, After harvesting, workers cut mother-of-pearl domes from the shell, fill them with epoxy, back with another piece of mother-of-pearl, and sell them as mabe “pearls.” Actually, they are not pearls at all, but mother-of-pearl domes.
They are relatively delicate organic gems produced by living creatures. Composed mainly of calcium carbonate in the form of the mineral aragonite (86%), cemented together with a different form of calcium carbonate called conchiolin (12%) and about 2% of water, pearls are built up in concentric layers-rather like an onion. Pearls themselves are not formed from the calcite flakes. They are laid down in a nearly spherical framework of conchiolin that, in many respects compares with the hexagonal cell formation of a honeycomb.
The most important organ of the mollusc is the mantle--a double flap the completely encloses the mollusc. The cells on the outer surface of the mantle have an amazing facility. They are able to produce pearl, and Mother of Pearl, by secreting the various components of the shell in a given order. The outer cells secrete a brownish substance (conchiolin) that forms the shell. Cells secreting calcium carbonate in the form of aragonite are nearer the centre, while the innermost cells of the mantle manufacture calcium carbonate in the form of calcite flakes. The flakes are produced so that they overlap like tiles on a roof. This is the layer that forms the smooth and beautiful Mother of Pearl bed on which the soft animal rests; the pearly lining seen inside many mollusc
shells.
When a “foreign body” gets inside the mollusc shell, such as a piece of grit, or a worm that has bored through the shell, the mollusc tries to ease the irritation that this causes by forming a layer of “nacre” (calcium carbonate) over the irritant and cementing it to its shell. This bulge on the shell, called a blister pearl, may eventually be removed and used as a jewel.
Spherical pearls are formed when a foreign body makes a depression in the mantle in such a way that a sac eventually develops around the irritant, which then becomes entombed in nacre. The size of the pearl depends on the amount of nacre laid over the irritant. Eventually, the pearl itself becomes the foreign body, and starts to be overlaid with more nacre.
