Cultured gems is a term used to describe pearls that are farmed and harvested from oysters. Pearls, which are formed when an irritant such as a grain of sand enters an oyster's shell, are considered to be one of the most valuable and sought-after gems in the world. Cultured pearls are created by introducing a foreign object into the oyster, which then secretes a substance called nacre to coat the irritant and form a pearl. This process is done in a controlled environment, allowing for the production of larger and more consistent pearls than those found in nature.