Enamel

Enamel is a dial material made from layers of colored melted glass.

The most common type of enamel dial in watches is Grand Feu ("big fire" in French) or vitreous enamel, which uses melted glass mixed with various types of metal oxides for color, lustre, and texture. Many layers of enamel are applied to a metal dial to give a deep luxurious finish. Enamel is notoriously difficult to work with, so it is considered a high form of hand-working in watchmaking circles.