have always formed in the soft tissue of mollusk
s living in saltwater and freshwater around the world, but their incidence is rare which gives them their high value. Rather than a Pearl forming around a piece of sand or grit, as many were taught, it is now known that Pearls are more likely a consequence of damage to the mollusk, as in an attack by another sea creature, a parasite or an injury.
When damage occurs, the mollusk sets to work to repair it, in a kind of immune system-like way. The mollusk begins to isolate the parasite or injury in secretions of calcium carbonate and conchiolin. They are laid down and form a sort of armature within a nascent Pearl sac, on which subsequent layers of this nacre
are laid down.
The likelihood of finding good looking natural Pearls is very slim. Many mollusks must be gathered and opened to find a single precious Pearl. All mollusks can produce pearls, but most lack the iridescent
and luminous qualities that are favored in jewelry-grade Pearls. Some are not very sturdy, as well as not being attractive, so they are of interest only to scientists and collectors.
Humans began searching for Pearls, as a bonus to the shells and meat of the mollusks, many thousands of years ago in the Indian Ocean. They would dive deeper and deeper, with cords attached so they could be hauled back up from the depths. Out of several tons of oysters, though, only three or four natural Pearls would be found that had the desirable shape, color and size that were coveted.
These difficulties led to the attempts to intentionally farm mollusks to grow cultured Pearls, which ultimately made them available to the general population, not just royalty. Cultured Pearls have only been grown since the early part of the last century, so any Pearl jewelry dated prior to 1916 is probably natural Pearl.
X-rays are used to distinguish natural Pearls from cultured Pearls. The x-ray shows the outline of a bead nucleus, which is implanted in mollusks by Pearl farmers. Natural Pearls will be nacre
right to the middle.
Some natural Pearls are so famous for their large size, perfect roundness and beautiful iridescence
, that they have been given names. One is the Abernethy (also known as Abernathy) Pearl, discovered by a diver of that name in 1967 in a river in Scotland. This was a large freshwater Pearl found in a mussel and was very round, white and translucent.
Another more recent find off the coast of California was an enormous, horn-shaped, multi-hued shiny Pearl found in a large abalone. Far from round, this giant Pearl was remarkable for its size and rainbow coloration.
Then there is the Hope Pearl, owned by the same man who possesses the Hope Diamond. It was found in a saltwater oyster, and weighs about four ounces. It is a Blister Pearl, formed attached to the shell, so is flat on one side, but, at two by four inches, its size alone sets it apart. It is primarily white, with some green on one end.
Natural Pearls come in many sizes, shapes and colors, and are formed in oysters, mussels, abalone and other mollusks, such as sea snails. Their variety and the combination of luck and industry that it takes to find them warrant their steep prices. Look for them in estate sales and auctions.