Pearl

Are cultured pearls "real" pearls?

Yes, cultured pearls are authentic pearls. They are made exactly the same way a natural pearl is in that a pearl oyster secretes the same mineral and protein around an irritant. The difference is that in a cultured pearl, the irritant is introduced by man rather than nature. To make a pearl, workers actually surgically implant a piece of tissue in freshwater pearl mussels, or a piece of tissue plus a polished bead (made from the shell of a freshwater mussel) into a marine pearl oyster. 

 

Varieties of Pearl

 

Freshwater Pearls are produced by various clam and mussel species, and are found mainly in the rivers of the UK , the former USSR and China . In general, these pearls have a far more subdued orient (the orient is the combination of interference and diffraction effects in the thin surface layers of the pearl) than oyster pearls, and are therefore beautifully suited to certain skin tones.

 

South Sea Pearls are among the largest harvested cultured pearls in the world. The average size of a South Sea pearl is 13mm, with most harvests producing a range of sizes from 9mm to 20mm. The South Seas lie between the northern coast of Australia and the southern coast of China. These waters are the native habitat of a large oyster known as Pinctada maxima, which can grow up to 12 inches in diameter. There are two varieties of Pinctada maxima: the silver-lipped and the gold-lipped. The two are distinguished by their distinct colouration of the outer edge of the interior. This type of shell is also known as mother-of-pearl, and is responsible for the colouration of the cultured pearls produced, hence the name.

 

Tahitian Pearls are cultivated from the black-lipped variety of the Pinctada maxima oyster, which reaches a foot or more in diameter and produces very large pearls. This oyster is very sensitive to the pearl culturing process, which makes the pearls very costly to produce. These pearls are traditionally called "black," but their colour can range from metallic silver to the colour of graphite. Within their range of colours they can have bluish, purplish, or greenish overtones.

 

Keshi Pearls are unique in the way they are formed. There are two ways that the pearl can develop, neither of which has to do with the 'usual' process of pearl production:

• The first way occurs when the oyster rejects and spits out the substance – the nucleus – before the development of the pearl finishes
• The second is when the nucleus fractures and forms two separate pearl sacs – circles of nacre – neither with a nucleus. Eventually, one or two nucleus-free pearls will usually form

Keshi pearls are also known as poppy seed pearls or seed pearls, as 'keshi' means poppy seed in Japanese, and they can result from either freshwater or saltwater pearls. As they do not have nuclei there is usually a large degree of variance in their shape, and they are often quite small. Keshi pearls come in a variety of different colours and shades, and are known for their lustre and uncommon orient, which results from their composition of solid nacre. Strangely, Keshi pearls are not given the classification of being a natural pearl as they are a by-product of the culturing process, and not something that happens naturally. Their variable shapes are frequently desirable to jewellers who wish to design something unique and inspiring and, as they are made of solid nacre, they have a superb lustre and therefore remain a very popular choice.

 

Mabé Pearls (or cultured blister pearls) are relatively large (1-20mm in diameter) and hemispherical in shape. They are produced by cementing the base of a hemispherical pellet of soapstone to the inside surface of the mollusc's shell. This material is chosen because the subsequent coating of nacre can easily be separated from its surface. The mollusc is then returned to the sea, where the pellet becomes covered with layers of nacre. After 2 or 3 years, the mollusc is recovered and the resulting pearl is sawn out of the shell. The soapstone bead is then removed from the pearl, the cavity cleaned out (and sometimes tinted) and either a smaller mother-of-pearl bead is cemented in its place, or the void is filled with a resinous compound. Finally, the base of the Mabé pearl is covered with a polished piece of mother-of-pearl.

 

How are pearls formed?

Any shelled mollusc can produce a pearl of sorts, but only those animals which have a shell with a pearl (nacreous) lining can form lustrous pearls worthy of use in jewellery. A pearl is formed when a small object or irritant becomes embedded in the tissue of an oyster or other mollusc, which then secretes nacre - a combination of crystalline and organic substances - around this irritant to protect itself. The nacre builds up in layers, eventually forming a pearl with the irritant at its centre. Natural pearls are those formed in this way by chance, which accounts for their rarity. Cultured pearls are made by placing a foreign object into the tissue of an oyster or other mollusc.

 

What gives pearls their different colors?

A pearl's natural color depends mainly on the species of mollusk involved. The color of the pearl tends to match the inside of the mollusk's shell—black pearls are made by the Black-lipped Pearl Oyster, gold pearls are produced by the Silver- or Gold-lipped Pearl Oyster, etc. The pigment resides in the organic layers, between the layers of aragonite, a crystalline form of the mineral calcium carbonate.

However, artificial coloring is not unknown in the pearl trade. Suppliers may dye, bleach, or irradiate pearls to alter their color.

 

How can I tell a real pearl from an artificial pearl?

Here's a traditional test—just rub the pearl gently across your teeth. A real pearl will feel gritty, but an artificial pearl will feel smooth and slippery. Remember, cultured pearls are real pearls, so they, too, will feel gritty.

This test works only on glass beads made to look like real pearls. Rubbed against the teeth, modern "shell pearl" imitations feel just like real ones.

How should I care for my pearls?
Pearls are much softer than other hard gemstones and can be easily scratched and damaged by metals or chemicals. Because they contain organic material and water, pearls can also crack if exposed to excessive dryness.

 

To protect your pearls

•  Store them in a soft cloth sack (an old cotton sock works well), separate from metallic necklaces, which could scratch them.
• Never clean your pearls in an ultrasonic cleaner. Vibrations can shatter them, especially if the nacre is thin or cracked.
• Do not use chemical cleaners, especially those containing ammonia and bleach, which will destroy their luster.
• Remove your pearls before washing dishes, doing housework, or applying perfume or hairspray. Chemicals like these can discolor or damage your pearls.
• Do not wear your pearls in swimming pools with chlorinated water.
• Avoid contact with foods containing acids like tomatoes, fruit juices, and salad dressings.
• Expose your pearls regularly to humid conditions. If you store your pearls in a safe, place a glass of water in the compartment with them.

 

To keep your pearls looking beautiful:

• Wipe your pearls with a soft cloth after wearing
• Sponge the surface of your pearls occasionally with mild soapy water; contrary to popular belief, the acidic oils and perspiration from human skin can damage the surface of a pearl.
• Have pearls restrung periodically (once every two years), especially if worn frequently. Most jewelers use silk thread with knots tied between the pearls to prevent abrasion and ensure that all are not lost if the string breaks.