Pearls of irregular and asymmetrical shape are termed baroque. Oysters grow pearls in many different shapes, from perfect spheres to long flat angel wing pearls. Surface perfection contributes to value. The surface of a perfect pearl appears satiny smooth. But when viewed closely, natural or cultured pearls may appear to have irregular surfaces which do not detract from value, as do disfiguring blemishes.
Rarity increases the value of any jewel.
Cultured pearls themselves are relatively rare, as they can only be grown in limited areas of the world's oceans and take years to grow. A perfect pair of pearls are very rare, because nature makes few pearls exactly alike in orient, size, shape and color. Types of pearls Akoya - The most familiar type of cultured pearl, grown in true pearl oysters off the coasts of Japan. Akoya pearls are known for their lovely orient and warm color. They rarely grow more than 9 mm in size.