The first category being the perfect pearl without any imperfections and an excellent lustre, and the
last category (or category D pearls) characterised by more than 60 per cent of light imperfections and
minimum lustre. Their colour is not only black as many people still think; they can possess a wide range
of colours (grey, white, yellowish, purple, and many others). This offers a very large array of possible
differentiation strategies and market niche opportunities.