Pearls fit into two categories: freshwater and saltwater. As their name implies, freshwater pearls are formed in freshwater mussels that live in lakes, rivers, ponds and other bodies of fresh water. Most freshwater cultured pearls sold today come from China. By contrast, saltwater pearls grow in oysters that live in the ocean, usually in protected lagoons. Akoya, South Sea and Tahitian are the three main types of saltwater pearls
The unique luster of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers become thinner and more numerous. The iridescence that some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black.
Cultured and natural pearls can be distinguished from imitation ones by a very simple test. Take the pearl and rub it (gently!) against the edge of a tooth. Cultured and natural pearls will feel slightly rough, like fine sandpaper, because of the texture of natural nacre. Imitations will feel as smooth as glass because the surface is moulded or painted on a smooth bead.
Pearls fit into two categories: freshwater and saltwater. As their name implies, freshwater pearls are formed in freshwater mussels that live in lakes, rivers, ponds and other bodies of fresh water. Most freshwater cultured pearls sold today come from China. By contrast, saltwater pearls grow in oysters that live in the ocean, usually in protected lagoons. Akoya, South Sea and Tahitian are the three main types of saltwater pearls
The unique luster of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers become thinner and more numerous. The iridescence that some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black.
Cultured and natural pearls can be distinguished from imitation ones by a very simple test. Take the pearl and rub it (gently!) against the edge of a tooth. Cultured and natural pearls will feel slightly rough, like fine sandpaper, because of the texture of natural nacre. Imitations will feel as smooth as glass because the surface is moulded or painted on a smooth bead. 
