Throughout the centuries, people have deemed pearls as one of the finest materials for jewelry. Their beauty is undeniable and they have become the epitome of rarity and refinement. However, what many people may not know is that the inside of the pearl looks just as beautiful, if not prettier, as the outside of it. Essentially, a pearl is formed when an irritant (usually a parasite) works its way into some type of mollusk. The animal then defends itself by coating the irritant in a fluid. The coating is called 'nacre' and layer upon layer of this coating forms a lustrous, glistening pearl.