Beading 101: Pearls


Published On: 04-08-2012 12:59am

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Category: Informational

4686Do you use pearls in your jewelry designs?  Need a better understanding of pearls and how they grow…

How Pearls are Formed

A pearl is a natural gem created by a living organism. When a foreign object is introduced into a mussel or oyster the animal coats the irritant with a substance called Layers of nacre build up to make a pearl.

 

Cultured Pearls

Most wild, natural pearl producing oyster beds have vanished due to over-fishing, oil drilling and pollution. Today, the world's most beautiful pearls are cultured.

Cultured pearls share the same properties as wild pearls. The difference is that a technician opens the shell and inserts the irritant which stimulates nacre production.

have a round shell bead (traditionally from an American freshwater mussel) grafted in as the irritant. This is called 'nucleating'. Oysters are suspended in water from rafts and at risk from typhoons, parasites, predators and algae.

have a small piece of mantle tissue (nacre producing tissue from another mussel) introduced as the irritant. This tissue desiccates leaving a solid pearl. Mussels are farmed in inland lakes and rivers.

Harvesting pearls is a time consuming business. Of the millions of oysters and mussels seeded each year, only a proportion (maybe just 50%) will survive to bear pearls. Of these, many will not produce pearls of a marketable quality.

Each pearl must be sorted by size, shape, color, lustre and blemish.   Then they need to be drilled and matched for stringing - a skilled and laborious task. To find 50 perfectly matched high-quality pearls for a 16 inch necklace a pearl processor may have to sort 10,000 pearls.

Pearl Shapes and Colors

Pearls come in a variety of shapes, colors and sizes. Round pearls traditionally command the highest prices but it's worth remembering that wild pearls were rarely round. Different shapes can give you a lot of pearl without breaking the bank.

Round Pearls are rarely perfect spheres unless they are of gem quality or imitation. The longer the pearl remains within the oyster or mussel the more chance there is of it developing an irregular shape. Very large round pearls are uncommon - and expensive. Even pearls nucleated with a shell bead have a hard time keeping their shape as they grow.

The term off-round is used to describe pearls which are 'roundish' to the eye but have a slightly oval or flattened shape. They can still have excellent qualities in terms of lustre or lack of blemish.

 

Oval Pearls are sometimes known as rice pearls. It comes from the very early days of Chinese freshwater pearl production when large numbers of low quality pearls entered the market and were derided as 'rice-crispies' after the cereal.   Oval pearls can form when two pearls in the same mollusc join together.

 

Baroque Pearls, Most natural wild pearls were off-round or baroque (a general term for irregular shape).  Bead nucleated pearls (pearls seeded with a round shell bead) may develop a tail on one side.  The most valuable baroque pearls are South Sea and Tahitian. Due to the length of time under cultivation a high percentage of the pearl harvest is baroque.

 

Button Pearls, So-called because of their shape - round on one side and flat on the other.

Keishi Pearls are accidents which happen when the mollusc rejects the nucleus and grows a 'free form' pearl.

 

Biwa Pearls: come from from Lake Biwa, a large freshwater lake near Kyoto in Japan. This was once the focus of the Japanese freshwater pearl industry. In the 1980's pearl production ceased due to industrial pollution.

Stick pearls, long natural freform pearls are sometimes called Biwa pearls.  Technically it is incorrect to call pearls Biwa unless they actually come from Lake Biwa.  Biwa became a generic name for all freshwater pearls regardless of their shape.

 

Pearl Colors

Pearls come in a variety of colors. Natural colors (white, off white, pink, grey, “black”) are mainly due to the breed of mollusc. Other influences include diet, water temperature and pollutants. No-one can predict or control what color pearls will be produced in any hatchery.


Black Pearls are rarely jet black but blue, green, grey, aubergine, peacock and more. Green is the predominant color.  Naturally colored black pearls come from the pearl farms of French Polynesia (Tahitian pearls) as well as Indonesia and the Philippines. 
Except for the occasional “mutant”, there are no natural black freshwater or Akoya pearls. The majority of 'black' pearls are treated in some way - it doesn't harm the pearl.


Nacre is crystals of calcium carbonate the same material that the mussels / mollusc use to create their shells.

 

Imitation Pearls, also called simulated, organic, faux and semi-cultured are made from beads of glass, ceramic or shell and coated with a varnish or laquer sometimes containing ground fish scales to mimic the pearl surface.

If you are not sure about your pearls being natural or imitation you can use the 'tooth test'. Gently rub the pearl against the edge of your top front teeth. Don't bite it.  A real pearl should feel slightly gritty due to its crystalline structure.  An imitation pearl will feel smooth. This is not an infallible test as tooth sensitivity can change how the "pearl" feels

 

I hope this helps you with your pearl buying experiance


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