The moon phase display is a rotating disc that displays the age of the moon through an aperture in the dial. It can be set by referring to a current lunar calendar. A complex complication, and unquestionably one of the most attractive displays.
Mother of pearl is the inner shell layer of certain molluscs, such as some mussels. As the material is very brittle, it has to be handled extremely carefully. The naturally developed nature of the material and its very individual shimmer and hue make each pearl dial totally unique - no one piece is quite like the next.