Cultured pearls are from the oyster family in the ocean or salt water. Freshwater pearls are from the mussel family and can be found in fresh water like rivers, lakes and ponds. Freshwater pearls are usually smaller, not round, and are much less expensive. Generally, an oyster must be 3 years old before sand can be inserted. Then, usually it takes at least 3 more years to form a beautiful pearl.
Larger pearls are more valuable than smaller pearls.
Round pearls are more valuable than less round. Generally black pearls are considered the most valuable. Pearl color and luster formation is a wonderful mystery of nature. There are many theories and explanations, but we believe no one knows for sure. Real pearls are made by nature, not by people.