Cultured pearls are precious jewels and should be treated as such. They are also the product of living creatures. Cultured pearls are formed when an irritant, commonly a grain of sand, is introduced into a mollusk. The mollusk secretes a substance called nacre, which covers the irritant and produces the pearl. Nacre gives the pearls their rainbow of color and luster that makes these gemstones so treasured, but it's delicate nature also makes pearls susceptible to damage. For this reason, you should be extra careful with your cultured pearls.