Pearlage

Pearlage is a term occasionally used to denote the formation, presence, or study of pearls within a mollusk. In contemporary scientific and commercial contexts, the process is more commonly described as pearl formation or nacre deposition rather than under the standalone term pearlage. The word itself is infrequent and may appear mainly in historical or niche writings.

Biology and process

Pearlage refers to the biological sequence by which a mollusk secretes layers of nacre, or mother-of-pearl, around an irritant or implanted nucleus. A mantle tissue or other foreign object provides a focus for nacre deposition, and over time concentric layers of calcium carbonate and organic matrix build up to form a pearl. The exact chemistry involves alternating layers of aragonite or calcite and organic matrix, producing the pearl’s characteristic luster. Natural pearls form without human intervention, while cultured pearls result from human-assisted insertion of a nucleus or tissue graft, after which the mollusk continues nacre secretion.

Types and factors

Pearls are categorized as natural or cultured, and as saltwater or freshwater. Cultured pearls can be bead-nucleated or tissue-nucleated, affecting shape, size, and internal structure. Quality factors include luster, surface smoothness, shape, color, and nacre thickness. Environmental conditions such as water quality, temperature, and nutrition influence pearl development, growth rate, and overall yield.

Significance

Pearlage-related knowledge underpins pearl farming and trade. Major pearl-producing regions include China (notably freshwater pearls), Australia, the Gulf of Eilat/Tahiti, and other parts of the Indo-Pacific. The term pearlage remains secondary to more precise language in contemporary references, but it appears in some historical or specialized discussions of pearl formation processes.