Pinna pearls — also known as “pen-shell” or “pen” pearls — are rare natural gems formed inside mollusks of the Pinnidae family. The pen shells from the Genus Pinna are found in various regions including the Mediterranean, Red sea, Indian and Pacific oceans, and the southern coasts of America. These pearls are unique due to their potential to form from both nacreous (mother – of – pearl) and non-nacreous material, and their colours range from white and orange to brown and black. Pinna pearls can be tear drop shaped or other irregular forms due to their formation within the shell.  While all Pinna pearls are relatively rare, those with vibrant colours and unique shapes can be quite valuable. The non-nacreous pearls may have a lower market value compared to the nacreous pearls, due to their tendency to crack.