The surface of a pearl is made up of many layers of nacre built up over time. The condition of its surface is evaluated according to its smoothness and the presence or absence of blemishes. . A blemish refers to any imperfection such as bumps, spots, chips, and ridges that is visible on the pearl’s surface. Because a pearl is a gem created by a living mollusc over time, a flawless pearl is rare. The extent of surface blemishes will affect the pearl’s allure and value.
Lustre is the magical element which creates the allure and eye appeal of a good pearl. It is the brilliance and reflectivity, or “shine”, of the pearl as light passes over and through the many layers of nacre and is reflected back to the viewer’s eye from deep inside the pearl. Lustre is evaluated on the degree of brightness observed, which in turn is influenced by the thickness of the nacre. Orient is the iridescent, shimmering play of colour which appears to glitter when the pearl is rotated, and generally enhancing the value of the pearl.
Lustre is generally regarded as one of the important aspect of a pearl’s quality and eye appeal - it is what separates the inferior pearl from the superior and the ordinary from the extraordinary.