How Are Pearls Formed

How Do Oysters Form Pearls

The process of pearl forming is actually remarkably similar to how we form blisters. Some kind of irritant like a piece of sand gets stuck inside the oyster, and then the oyster secretes a fluid called nacre to protect itself. Over the years this coating forms a smooth surface to completely cover it. 

What actually gives pearls their complexity and glow is a substance called aragonite. For low lustre pearls the aragonite is perpendicular to the surface of the pearl, so we don't get much glow because the light is passing right through it, like looking through the water. 

The glowing pearls that really catch your eye are like rainbows forming from droplets of water: the light is fractured by many different overlapping layers of aragonite. 

Farmed Pearls

Of course, not all pearls are formed in the wild. Clever humans have realized ways to create far more pearls by implanting the substance that will form the seed for the pearl. First the oysters are raised until they are old enough to form a pearl, the implantation occurs, and then with a little luck a beautiful pearl will be formed 1-3 years later. There are two methods of implantation:

Grafting

I find this fascinating: a piece of one oyster is grafted onto another oyster! The grafted piece forms nacre, and then the oyster forms nacre on top of that, oysterception!!

Bead Nucleation

A lot more boring and obvious, bead nucleation is done by inserting a small bead or irritant into the oyster, when then forms the pearl around it. This method is a lot more efficient and generates larger pearls, however. 

Kennedy, Jennifer. "How Pearls Form and Which Species Makes Them." ThoughtCo, Apr. 5, 2023, thoughtco.com/how-do-pearls-form-2291787.