What is a mabe in terms of pearl formation?

A mabe, in terms of pearl formation, refers to a unique type of pearl that is cultivated in a way that forms a dome shape as opposed to being a fully rounded pearl. It is characterized by its layered structure of nacre, which is the same material that forms the inner shell of mollusks. This nacre is responsible for the iridescent qualities of pearls. The backing, usually made from a solid material, supports the nacre layer, giving the mabe its distinctive shape and appearance.

Unlike fully spherical pearls, which develop inside the body of an oyster or mollusk, mabe pearls grow against the inside wall of the shell, leading to their unique half-pear-shaped structure. This distinctive cultivation method is an important factor in their classification as they are often used in jewelry as a striking centerpiece due to their shape and luster, which can sometimes be emphasized by their backing.

In contrast, the other options do not accurately define what a mabe is: a type of gemstone variety does not specify the unique nature of mabe pearls, a chemical treatment used on pearls does not relate to their natural formation process, and a gemstone carving technique is unrelated to how mabe pearls are formed. Therefore, the layered structure of