Usually pearls are produced – or cultivated – from mussels and oysters, which can give birth to the most known and appreciated types of pearls with the typical mother-of-pearl composition. But not everybody knows that even the most common clams are able to produce pearls without nacre.
Theoretically every bivalve could be albe to produce pearls, for this reason every single pearl created by a bivalve – independently of the typology – is called “Clam pearl”; nevertheless these findings have mainly happened with the Meretrix lusoria clam, fished mainly in the North-Eastern coasts of America for its tasty fruit.
The absence of nacre in the pearl’s composition doesn’t affect it value at all, which is immoderately balanced out not only by its rarity but also for the characteristic structure this pearl owns: needle-like pillar structure which can vaguely a luminous pattern with little flames that radiate from below the surface of the pearl.
Beside this particural conformation – the most sought, so the most valuable one – these pearls can have different colors and different sizes which have to be calculated in kilograms instead of carats.