How Do Pearls Get Their Round Shape?

November 24, 2015 by Melissa

 

pearl shape

Pearls are a beautiful byproduct of a natural defense mechanism – when an oyster senses that its shell has been invaded by a foreign particle, it coats the irritant in nacre in order to protect the oyster’s soft insides. Nacre is a naturally-occurring material produced by the oyster which builds up around the invader and keeps the oyster safe.

But it is precisely because the pearl is a naturally-occurring gem that it is expected to come in shapes and colored as varied as oysters themselves. Still, many pearls have a symmetrical shape – something not normally occurring in nature. How does this happen? Obviously, while we understand the overall process of pearl formation, we do not know the specifics of what occurs in the shell. But given the oyster’s ability to form pearls with symmetry that appears to be formed around an “axis,” the belief is that some pearls actually rotate inside of a shell during the formation process. But what forces the pearls to rotate?

Scientists believe that as nacre builds upon itself around the irritant, the new nacre ions release thermal energy. As water hits this warmed surface, it creates a force which “pushes” the pearl and forces it to rotate. Scientists say that this “push” from the water acts like a series of little motors, slowly spinning the pearl and making the “rotational axis” symmetrical shape which, at first glance, seems to defy the irregular nature of most gemstones. Once again, pearls have found a way to remind us that even with all of the beauty offered by Mother Nature, pearls are one-of-a-kind.

Click here to learn more about pearls.