"Flat Pearl", also known as "Siu Chu", refers to pearls without any modification or perforation.

Pearl is an organic gem, produced by shellfish. When foreign objects invade shellfish, in order to protect themselves, shellfish will secrete nacre to surround them, thus forming pearls. According to the environment, pearls can be divided into freshwater pearls and seawater pearls. In addition, it can be classified according to its appearance characteristics. The common uses of pearls include jewelry making, ornaments, medicine and other fields.