Formation and Classification of Pearls

Pearls are oldest gems known and are still popular for the meaning they convey and the history and facts behind them. A pearl's formation contains CaCO3 calcium carbonate and a little water.
Pearls are mainly classified into two types. They are:
1. Natural
2. Cultured
More than 95% of the these stones produced and available today in the market are cultured. It is very rarely to find and buy a natural pearl these days. So they are very expensive too.
Natural Pearls
These can be further classified down to
1. Salt water - Found in Gulfs, coasts, oceans and bay areas
2. Fresh water - Found in rivers and lakes.
These are produced by a living creature under the natural environmental conditions. The mollusk secretes layers of nacre around an irritant (this becomes the nucleus later) to protect itself. This irritant enters the mollusk by an act of nature. This irritant can be anything small like sand, snails, worms, or any other small living creatures. But it is believed that this irritant is sand.
Natural pearls are very rare these days because of the increase in water and air pollution. As pearls are very much sensitive to the natural weather conditions, the production of these pearls has fallen drastically.
Cultured Pearls
Similar to the natural ones, these are also divided to salt water and fresh water pearls. Today, the production of these pearls has rose to more than 95% of the total World's pearl production.
Saltwater gems are round in shape and cost higher than the freshwater pearls. But the fresh water pearls are available in more colors and shapes. In the cultured pearls, man injects an irritant substance into the mollusk. The formation of a complete pearl takes up to 5 years of time and all during this time the pearl farms have be taken care with extra caution from pollution.
I have been very much interested and associated with pearls for over a decade now. A follower of fashion industry and jewelery trends, I write for a local magazine and run few blogs. I also shop for pearl ring jewelry often.