Pearl harvesting begins with carefully opening the oyster shell just enough to access the mantle tissue without damaging the animal. The mantle is the organ responsible for secreting nacre—the composite material that ultimately forms a pearl. In pearl aquaculture, technicians typically implant a nucleus (often a polished bead made from freshwater mussel shell) along with a small piece of donor mantle tissue into the host oyster. The donor tissue contains epithelial cells that begin forming a pearl sac around the nucleus. Over time, this sac deposits successive layers of nacre composed of microscopic aragonite platelets bound together with organic proteins and chitin. Nacre is a natural nanocomposite material. Its layered microstructure—often described as a “brick-and-mortar” arrangement—gives pearls their strength, durability, and characteristic iridescence. Light interference between these ultra-thin layers produces the optical effect known as orient, responsible for the pearl’s glo...