Although Akoya, Tahitian, South Sea and Freshwater pearls are the four dominent pearl varieties found commercially, there are a number of other interesting and beautiful types of pearls.

• Keshi pearls are formed accidently as a by-product of mollusk nucleation.  They are thought to form from tiny fragments of mantle tissue that disperse through out the oyster or mussel.  They can be small or large and are almost always of irregular shape.
  
• "Oriental" pearls are natural pearls found around the Red Sea and Persian Gulf region.
  
• Mabé pearls are formed from irritants that lodge along the surface of the mollusk shell, they are dome shaped with a backing of Mother-of-Pearl afixed.
  
• Abalone, conch and melo melo pearls come from are among the less commonly encountered types of pearls found commecially.  In the case of conch and melo melo pearls, these are called calcareous concretions and are non-nacreous.  Their look is altogether different than that of the more traditional nareous pearls.