In the wild, seawater oysters and freshwater mussels, can occasionally, find themselves in a similar irritating, painful situation should a foreign body find its way inside their hard outer shells into their soft, fleshy body.
If it can’t eject the intruder; by pumping water through its shell–equivalent to us shaking our foot – the mollusc (the group name for shelled creatures) decides it has to live with it and special cells from the edge of the mollusc called epithelial cells start to encircle the intruder to form a kind of “cocoon” called the Pearl Sac. Inside this cocoon, the mollusc deposits the substance it uses to build its shell known as “Nacre”.
Nacre is composed mainly of Calcium Carbonate; a mineral which in Humans builds bones and teeth.
In molluscs the substance occurs in the form of Aragonite crystals which build up in concentric microscopic layers around the irritant; a little like slates on the roof of a house. These “slates” are bound together by another substance secreted at the same time called Conchoilin – a kind of organic glue.Layer upon layer of coatings build up over time and eventually with luck, and if all the conditions are right a Pearl will form.
Contrary to common belief, a grain of sand is not the cause of a pearl in the wild as the mollusc can easily flush this out of its shell.Sharp pieces of debris,tiny creatures that slip into the shell during filter feeding, and natural boring parasites, however will all cause some kind of injury to the soft inner tissue of the Oyster and trigger the coating process.
Natural pearls have been prized for thousands of years as natures ultimate treasure.
They are unique,formed by the serendipity of organic nature and one might compare their creation to the miracle of childbirth – each one unique and beautiful.
Diamonds and all other hard stones however, are formed by the brutal processes of inorganic nature and owe their conception to violent pressure, heat and eventual cooling and crystallisation.
Throughout the ages natural pearls, sometimes called “Orient Pearls”, have been referred to by religious texts and historians. From antiquity until the last century the main oyster beds were found in the Persian Gulf. Countries such as Bahrain and Qatar would sell their pearls to Indian merchants who would drill and thread the pearls in to small hanks (short collections of threaded pearls) known as “Bombay Bunches” for resale to the European trade.
Today, mainly due to pollution and scarcity, the majority of the natural pearls found for sale are “regenerated” pearls that were originally found by divers very many years ago. In Scotland the River Tay, in the vicinity of the town of Perth, still has a reputation for producing natural freshwater pearls.
It is known that Queen Victoria owned some very fine examples. This gives and indication of the regard in which these gems were held. Large, round natural Pearls of good quality are so rare that they rank along side the most valuable of all gems.