Pearls are formed in oysters or mussels. The emergence of a pearl is caused by the defense mechanism of the animal. When something strange like grains of sand, remnants of an oyster shell or accidental parasites invade the glands respond to this by the pearl oyster to separate on the intruder around. After a few years this intruder has become a beautiful pearl. The difference between a breeding pearl or freshwater pearl and a "real" pearl is a pearl formed in nature by an accidental "intruder" and the culture pearl is nature a helping hand by the man who is an "intruder" in the shell places. "Real" pearls and pearl farming are both real pearls. Pearls should however be provided. When they are not cared for it will age quickly, they are dull and finally the pearly layers starts to release. To avoid it would be contact with perspiration, perfumes, cosmetics and cleansers should be avoided. Rub the pearls occasionally with a chamois or a piece of velvet.