Surface Features and Internal Structures of Non-nacreous Pearls from Pinctada maxima.

Non-nacreous pearls are derived from some marine gastropods and bivalves; a small percentage of these pearls have their surface composed of calcite instead of aragonite. This study provides a detailed characterisation of a five-row graduated necklace consisting of non-nacreous pearls reportedly sourced from the Pinctada maxima mollusc, which typically produces nacreous pearls. Raman analysis showed that their surface consisted of calcite, and microscopic examination revealed a diverse array of surface features. Real-time X-ray micro-radiography showed internal structures mostly consistent with non-bead-nucleated cultured pearls, although some exhibited internal growth structures resembling natural pearls. Considerable effort is required to gather, match and drill such a substantial quantity of non-nacreous pearls, given their susceptibility to damage. [ABSTRACT FROM AUTHOR]