Cultured Pearls
Cultured pearls are the kind you will find most frequently for sale today.
To understand what a cultured pearl is, you need to understand how natural pearls occur. Most pearls are created when a small parasite or intruder enters a mollusk. The mollusk protects itself from the foreign object by secreting a substance called "nacre." This continues for some time, and can eventually result in a beautiful pearl.
The problem with these natural pearls, which were the only type that existed for many years, is that large numbers of mollusks must be opened up to find just one that contains a pearl. This makes natural pearls very expensive.
Cultured pearls are created by inserting a small bead into an oyster, creating an artificial irritant that causes it to secrete nacre. After several months, the oyster has created a pearl. These pearls are also beautiful - if x-rayed, the difference between a cultured and natural pearl can be seen, but without an x-ray, the average person cannot tell the difference.
Due to the prohibitive cost of natural pearls (particularly if looking for a matched set), we highly recommend purchasing cultured pearls for your jewelry. This page has links to several well priced cultured pearls at Amazon, or please look at the selection Jewelry Impressions
has available.