A pearl necklaces 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 nacre, the same material with which it builds it's shell. Over time, the layers of nacre build up to form the pearl. The longer the irritant remains in the mollusc, the more layers of nacre and (usually), the better the pearl.Each pearl must be sorted by size, shape, colour, lustre and blemish. Then they need to be drilled and matched for stringing - a skilled task.

Most wild, natural pearl producing oyster beds have vanished due to over-fishing and pollution. Today, the world's most beautiful pearls are cultured. Cultured pearls share the same properties as natural pearls. The only difference is that a technician opens the shell and inserts the irritant. Nature then takes over. Freshwater mussels are suspended in the water in inland lakes and rivers from rafts above and are subject to typhoons, parasites, predators and even barnacles.
Harvesting pearls is a time consuming process. Of the millions of 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.
Freshwater pearls are processed all over the pearl producing regions in China and Hong Kong. Careful bleaching and polishing can take between one to two months. The freshwater pearls come out of the shell in natural pastel colors ranging from white to pinks and lavenders. Irritation and other processes to create black and darker colors in freshwater pearls also occur at this time.

How to test if a pearl jewery is genuine (http://www.pearl-necklaces-jewelry.com/faq.html)

There are several ways to test whether a pearl is genuine. The simplest way is to gently rub two pearls together. The surfaces should be slightly gritty indicating authentic pearls. Should the surfaces glide smoothly over each other this indicates the pearls are imitations.
Real pearls are cold when you touch them. You don't feel the coolness when touching fake pearls. They always have the same temperature as the room air.
Real pearls are heavy in weight. Fake pearls are light in weight.Real pearls reflect light beautifully and their luster looks very natural. The luster of fake pearls doesn't look natural. It looks like glass.(There is some Mother of Pearl jewelery on this website, Mother of Pearl is coated (nickel and lead free) so it has a smooth feel to it, therefore it does not feel gritty when touched. Some customers prefer Freshwater Pearls and others prefer Mother of Pearl. Each item is clearly described so you can tell which is which.)

Valuing Freshwater Pearls

The value of freshwater pearls and finished pearl jewelry pieces are varied.The following factors play a role in valuing Freshwater Pearls.
Luster
The shine or luster of a pearl is defined as how well the pearl reflects light. One way to think about luster is to imagine a mirror. The more light reflected and clearer the image, the better the pearl's luster.

Size
The size of the pearl also effects the value. A larger pearl with similar other value factors will gnerally be more valuable than a smaller one.

Matching
The pearls in a jewelry piece should be well matched in color, size and quality. For freshwater pearls, with their varying natural colors, color matching is very important.

Cleanliness
Another pearl value factor is the cleanliness of the body or surface of the pearl. The less visible spotting, the more valuable the pearl. Pearls are a naturally formed organic gem so some minor surfaces blemishes are perfectly acceptable.

Caring for your pearls
Put your pearl jewelery in a soft bag, a velvet box or a satin pouch. Pearls should not touch other jewelry or hard objects.
• Since pearls contain calcium carbonate, they can be damaged by acids. Protect pearls from chemicals such as vinegar, alcohol, ammonia, and hair spray, bleach, perfume, swimming pool water, and cosmetics. You should put on your pearls after you have applied makeup, hair spray and perfume.
• Avoid wearing pearls when you sweat since sweat contains acid. Remember to take pearls off when exercising, swimming or taking a shower.
• Pearls contain organic substance. They need fresh air and moist. Wear pearls at least once every month.
• Wipe pearls regularly with a soft cloth moistened with water. Pearls can absorb perfume and skin oils as well as dirt.
• If you scratch a pearl skin, use olive oil to gently rub on the scratched area.
• If you wear pearls frequently, it is advisable to restring the pearls every one or two years before the silk thread weakens.