Pearl Information Guide
Lustre & Surface
Lustre is not simply a shiny, reflective surface, but rather an inner glow which results from the rays of light travelling through the numerous layers of nacre and being reflected from within the pearl. This effect can only occur when the pearl coating is thick. If a pearl has an excellent lustre, small marks or spots on the surface are not so noticeable. As with diamonds, which almost always have internal flaws or inclusions, such marks should be considered characteristics rather than imperfections.
