Some more information about pearls

I found some more interesting information about pearls 

A pearl is a hard object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate  in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable.

The most valuable pearls occur spontaneously in the wild, but they are extremely rare. Cultured or farmed pearls from pearl oysters make up the majority of those that are currently sold. Pearls from the sea are valued more highly than freshwater pearls. Imitation or fake pearls are also widely sold in inexpensive jewelry, but the quality of their iridescence is usually very poor, and generally speaking, artificial pearls are easily distinguished from genuine pearls. Pearls have been harvested and cultivated primarily for use in jewelry, but in the past they were also stitched onto lavish clothing. Pearls have also been crushed and used in cosmetics, medicines, and in paint formulations.

Pearls that are considered to be of gemstone quality are almost always nacreous and iridescent, wild or cultured, like the interior of the shell that produces them. However, almost all species of shelled mollusks are capable of producing pearls of lesser shine or less spherical shape. Although these may also be legitimately referred to as "pearls" by gemological labs and also under U.S. Federal Trade Commission rules, and are formed in the same way, most of them have no value, except as curios.

Creation of a pearl

The difference between wild and cultured pearls focuses on whether the pearl was created spontaneously by nature or with human aid. Pearls are formed inside the shell of certain mollusks as a defense mechanism against a potentially threatening irritant such as a parasite inside its shell, or an attack from outside, injuring the mantle tissue. The mollusk creates a pearl sac to seal off the irritation.

The mantle of the mollusk deposits layers of calcium carbonate in the form of the mineral aragonite or a mixture of aragonite and calcite held together by an organic horn-like compound called conchiolin. The combination of aragonite and conchiolin is called nacre, which makes up mother-of-pearl. The commonly held belief that a grain of sand acts as the irritant is in fact rarely the case. Typical stimuli include organic material, parasites, or even damage that displaces mantle tissue to another part of the mollusk's body. These small particles or organisms gain entry when the shell valves are open for feeding or respiration. In cultured pearls, the irritant is typically an introduced piece of the mantle epithelium, together or without a spherical bead.

Natural pearls are nearly 100% calcium carbonate and conchiolin. It is thought that natural pearls form under a set of accidental conditions when a microscopic intruder or parasite enters a bivalve mollusk, and settles inside the shell. The mollusk, being irritated by the intruder, forms a pearl sac of external mantle tissue cells and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl. Natural pearls come in many shapes, with perfectly round ones being comparatively rare.

Typically, the build-up of a natural pearl consists of a brown central zone formed by columnar calcium carbonate and a yellowish to white outer zone consisting of nacre. The presence of columnar calcium carbonate rich in organic material indicates juvenile mantle tissue that formed during the early stage of pearl development. Displaced living cells with a well-defined task may continue to perform their function in their new location, often resulting in a cyst. Such displacement may occur via an injury. The fragile rim of the shell is exposed and is prone to damage and injury. Crabs, other predators and parasites such as worm larvae may produce traumatic attacks and cause injuries in which some external mantle tissue cells are disconnected from their layer. Embedded in the conjunctive tissue of the mantle, these cells may survive and form a small pocket in which they continue to secrete their natural product: calcium carbonate. The pocket is called a pearl sack, and grows with time by cell division; in this way the pearl grows also. The juvenile mantle tissue cells, according to their stage of growth, produce columnar calcium carbonate, which is secreted from the inner surface of the pearl sack. With ongoing time the external mantle cells of the pearl sack proceed to the formation of tabular aragonite. When the transition to nacre secretion occurs, the brown pebble becomes covered with a nacreous coating. As this process progresses, the shell itself grows, and the pearl sack seems to travel into the shell. However, it actually stays in its original relative position within the mantle tissue. After a couple of years, a pearl will have formed and the shell might be found by a lucky pearl fisher.

Cultured pearls are the response of the shell on a tissue implant. A tiny piece of mantle tissue of a donor shell is transplanted into a recipient shell. This graft will form a pearl sac and the tissue will precipitate calcium carbonate into this pocket. There are a number of options for producing cultured pearls: use freshwater or seawater shells, transplant the graft into the mantle or into the gonad, add a spherical bead or do it non-beaded. The large majority of saltwater cultured pearls are grown with beads, the trade name of the cultured pearls are Akoya, white or golden South sea, black Tahiti. The majority of beadless cultured pearls are mantle-grown in freshwater shells, tradename Chinese cultured pearls.

Cultured pearls (beadless or beaded) and imitation pearls can be distinguished from natural pearls by X-ray examination. Nucleated cultured pearls are often 'pre-formed' as they tend to follow the shape of the implanted shell bead nucleus. Once the pre-formed beads are inserted into the oyster, it secretes a few layers of nacre around the outside surface of the implant before it is removed after six months or more.

When a cultured pearl with bead is X-rayed, it reveals a different structure to that of a natural pearl. A beaded cultured pearl shows a solid center with no concentric growth rings, whereas a natural pearl shows a series of concentric growth rings. A beadless cultured pearl (whether of freshwater or saltwater origin) may show growth rings, but also a complex central cavity, witness of the first precipitation of the young pearl sac.

Original/unedited content may be found at Wikipedia.org

Natural Pearls vs. Cultured Pearls

Pearls evoke a sense sophistication, style and opulence. Pearl jewelry, such as pearl necklaces, rings, earrings and bracelets, complement a variety of outfits and can add a lot to your wardrobe. When you are shopping for pearls, you will encounter a variety of different types and you may be wondering which ones are right for you. There are distinct differences between naturally occurring pearls and cultured pearls, as well as differences between freshwater and saltwater varieties. Understanding the differences will help you make an informed decision when purchasing pearl jewelry.

Cultured and Natural Pearls:

Natural pearls and cultured pearls are created in different ways. Natural pearls occur in the wild, without any human assistance. They are hunted and are quite rare. When found, the pearls are harvested, cleaned and made into jewelry. Cultured pearls, on the other hand, are grown under tightly controlled conditions by pearl farmers. Farmers plant a core made up of mussel shell into an oyster or mussel; then the oyster or mussel forms a pearl around this irritant, just as they do when forming natural pearls. Pearl farmers design cultured pearls from start to finish, ensuring they are perfectly shaped and luminous. Once harvested, the pearls are cleaned, and some are treated and bleached before being made into jewelry. Both natural and cultured pearls can be freshwater or saltwater pearls. Freshwater pearls are created or occur in mussels, while saltwater pearls are created or occur in oysters.  

 

 

 Natural pearls and cultured pearls have different features. Natural pearls vary in size and luminosity, though most have a stunning iridescent quality. They are also found in a variety of shapes and sizes simply because they are wild. Cultured pearls have some of the same qualities, but they will most often be uniformly shaped and sized, and they can also be dyed or bleached to achieve different colors and luster.  

 

 

 

Natural pearls and cultured pearls have different price ranges. Because natural pearls are rare and difficult to find, they are typically quite expensive. Perfect strands of natural pearls are even more uncommon and can be among the most expensive pieces of jewelry. Cultured pearls can also be expensive, depending on their luster, shape and size, but are available in a range of prices. Both natural and cultured pearls of all varieties can be a valuable jewelry investment, so shop for and purchase your pearl jewelry carefully. 

 

 

 

Cultured pearls are often thought of as imitation pearls, but the two should not be confused. Cultured pearls are made of the same material as natural pearls and take time to create, up to seven years depending on the type of pearl. Imitation pearls are often made of plastic or glass and can be manufactured quite easily and quickly. Keep this in mind when you are shopping for pearl jewelry.

 

Special thanks to the author Lynda Belcher.

Magnetic Bracelets Benefits Explained

 

Magnetic jewelry has become a very popular way to treat a myriad of health conditions and problems. You may be wondering what magnetic bracelets actually do and whether or not magnetic jewelry works to relieve pain. In this article, we will review the different types of magnetic jewelry and try to make sense of magnetic bracelets benefits and promises. There are many sources of information about magnet therapy, and it can be difficult to decide whether or not to try magnetic bracelets. Our quick overview simplifies magnetic bracelets benefits and can help you approach magnet therapy in the right way.

Basic information about Magnetic Bracelets:

Magnetic jewelry choices: Magnetic jewelry is available in many different styles. Many magnetic bracelets offer their own unique style aesthetic. Choose from magnetic cuff bracelets with simple details, magnetic jewelry with pearls and gemstones and handsome magnetic link pieces. Magnetic necklaces and rings are also available; if you find that your magnetic bracelet is beneficial for your health, consider adding other magnetic pieces to your collection to maximize benefits.

Magnetic pain relief: Magnetic therapy is the idea that magnets increase circulation, blood flow and oxygen in a specific area in the body. Increased blood flow can help to relieve pain and stiffness, especially if your joints, back or muscles are swollen or injured. Many individuals with arthritis and other chronic pain conditions report relief from magnet therapy.

Magnetic mental therapy: Magnet therapy has also been shown to increase relaxation and well-being in some individuals. This may simply reflect the reduction in pain and stiffness, or it may be its own benefit. Many proponents of magnet therapy say that magnetic bracelets restore the body's natural energy field or help align the body's chakras. Either way, relaxation is a very important part of physical health. Consider magnetic therapy to deal with daily stress and tension.

Try it for yourself: Effects of magnet therapy have not been medically proven, but each individual should decide for themselves if magnetic jewelry is right for them. Many people have exhausted other pain-relief remedies, and magnetic bracelets may be a good solution for individuals with chronic, untreatable pain. Try stylish, affordable magnetic bracelets, rings or necklaces for yourself.

The content in this article are not intended to substitute for the advice of a qualified physician, pharmacist or other licensed health-care professional. Any products mentioned may have additional information and instructions on or inside the packaging that you should carefully read and follow. Contact your health-care provider immediately if you suspect that you have a medical problem.

Special Thanks to Maegan Crandall for this magnificent article.