Pearl are one of the most precious types of jewelry. It's also known as "organic gems" since they are formed by shellfish, pearls have been harvested and worn for more than 4,000 years.

A pearl is formed when a foreign material or parasite enters the shell of an oyster and cannot be expelled. To reduce irritation, the oyster coats the intruder with the same semi-translucent crystalline material called "nacre" it uses for shell-building. The oyster deposits layers around the object. The longer the material stay, the thicker the nacre layer that the oyster puts on it (pearl). The thicker the nacre layer, the more expensive the pearl.