Contrary to common belief, a grain of sand is not the cause of the formation of a pearl. Molluscs (Oyster and mussels) spend their time filter feeding on the beds of the environment in which they live and can flush these tiny grains this out of their shells.
If however, a sharp fragment finds its way in, and the mollusc can’t eject, its defence mechanism is to deposit around the intruder the substance it uses to build its shell called nacre (a type of Calcium Carbonate in the form of Aragonite).This nacre builds up in layers to eventually form the pearl.
This natural reaction will occur regardless whether the mollusc is a Seawater Oyster or Freshwater Mussel.
These are any type of pearl in which the irritation has been deliberately set up by man to induce the mollusc to coat the irritant.Posted: July 30, 2020Categories: Pearls