Pearl, the birthstone for June, is one of the most famous gems, arguably only second place to the diamond. Our collective consciousness is filled with paintings of European royalty donning pearl necklaces and pearl earrings and pictures of Hollywood's elite wearing pearl rings. Pearls are classified in two ways: natural or cultured.
Natural pearls are discovered using pearl hunting. Pearls form inside mollusks within the sea after an irritant finds its way into the mollusk. Pearl hunters would identify mollusk beds and removed in large clusters from the ocean bottom. This method proved to be inefficient because out of hundreds of mollusks only very few contained pearls. Because for hundreds of years this was the only way to procure pearls, pearl jewelry was quite expensive. This changed, and the price of pearls came down, once cultured pearls were introduced into the market.
Cultured pearls form in pearl farms. Humans introduce an irritant into each mollusk and then collect the pearls when they have formed. This method costs less than pearl hunting and its pearl yields are more predictable.