You are at a clam bake feasting on the most delicious of meals ..... is it possible that little stone in your mouth is not a piece of shell or broken tooth but a natural pearl? Maybe. Could it be valuable? Most aren't but some can be.
The truth being told-- all shelled mollusks have the possibility of producing pearls but they are not all created equal..... many do not have the qualities of a true gem.
The largest Pearl ever found is now referred to as Pearl of Lao Tze (known also as the Pearl of Allah). This Pearl is the most famous Clam Pearl ever found.
Giant Clams have no mother of pearl on the inside but are like porcelain. This means that any pearl that forms in them look like porcelain rather than like traditional nacreous pearls. A giant clam can produce something that is quite large but it will lack the iridescence of a pearl produced from an oyster or mussel. A pearl produced from an oyster will be much smaller but because of the iridescence will be considered a gem.
The luster of the oyster pearl comes from the reflection, refraction and diffraction of light from the many translucent layers of nacre that make up the pearl. Crystals in each layer overlap those in the preceding layer causing the light to defract. The thinner the layers and the more layers of nacre there are the more outstanding the luster.
Although it is very large, the Pearl of Lao Tzu does not have the luster of a nacreous pearl. It is more comparable to porcelain in look and texture. Most pearls found in edible clams similarly are not lustrous nor iridescent and hence have little or no value as gems.
Having said that, some non-nacreous pearls are very beautiful - and valuable. Some species of clams produce non-nacreous pearls with very high luster and a flame pattern that sparkles from deep within the pearl. According to the species of clam they may be white or purple or brownish. Some can fetch a high price. There was a time when non-nacreous pearls weren't considered pearls. But now they are classified as pearls and treasured for their beauty - even though they're a different type of pearl.
So what about that pearl you found at the clam bake? Pearls don't react very well to heat, so it would likely have been damaged by cooking. Most pearls found while eating edible oysters and clams are small, sometimes not that attractive, and often don't have that all important lustre and iridescence. These pearls are not going to be worth much if you try to sell them. But they are terrific momentos of the excitement of discovering a natural pearl and are invaluable as keepsakes and the basis for a great story!
If you find one that is very beautiful remember to photograph the shell of the oyster or clam it came out of, and record where and when it was found so the species can be identified if you ever decide to sell it.
So next time you are clam digging and come across a non-nacreous pearl enjoy it for its own beauty but don't be disappointed if it's not as valuable as it's oyster pearl counterpart.
All the Pearls offered here at Pearl Distributors are 100% gemstone pearls produced from oysters or other mollusks with high quality nacre found in either sea water or fresh water.