Natural pearls are extremely rare. Historically, many were found in the Persian Gulf; unfortunately, today, most have already been harvested. You may be able to purchase small, natural pearls, but they will be costly.
Cultured pearls are grown in pearl farms. The mollusks are raised until they are old enough to accept the mother-of-pearl bead nucleus. Through a delicate surgical procedure, the technician implants the bead and then the mollusks are returned to the water and cared for while the pearl forms.
Not all produce a pearl; and not all the pearls are high quality. Over 10,000 pearls may be sorted before a 16" single strand of beautifully matched pearls is assembled.
Pearls can be found in saltwater and in freshwater. There are also different types of mollusks that produce very different looking pearls.
Saltwater pearls include the akoya cultured pearls grown in Japanese and Chinese waters. They range in size from 2mm (tiny) to 10mm (rare) and are usually white or cream in color and round in shape.
Australia, Indonesia, and the Philippines produce the South Sea pearl – the largest of all the pearls. They range in size from 9mm to 20mm and can be naturally white, cream, or golden in color.Nowadys Burmese pearls( Myanmar) also is getting famous and quality also unique (Superior golden colour).
Tahitian pearls are interestingly not exclusively from Tahiti – they're grown in several of the islands of French Polynesia, including Tahiti. Their typical sizes range from 8mm to 16mm. These naturally colored pearls are collectively called black pearls, but their colors include gray, blue, green, and purple.
These pearls are grown in freshwater lakes, rivers, and ponds, predominately in China. Although many are white and resemble the akoya cultured pearls in shape and size, they can also be produced in various shapes and in an array of pastel colors.
Many freshwater pearls don't have a bead nucleus — only a piece of tissue — resulting in a pearl with thicker nacre than the akoya.