The favored material used today to bring luminescence to the watch dial for easy night and underwater reading is Super-LumiNova - developed just about two decades ago in the early 1990s.
Super-LumiNova is non-radioactive and is a strontium aluminate substance created in a host of colors that enable the watch numerals, markers, hands and other dial accents to glow blue, green or even red-orange depending on the mixes used. Over the decades, the material has advanced thanks to a great deal of research and development, and the Super-LumiNova of the early 1990s has evolved into a new intensity that is at least double the strength of the early versions. Super-LumiNova can be as much as 10 times brighter than the previous zinc sulfide-based materials, and is applied in varying strengths.
After absorbing sufficient UV light, the phosphorescence glows in the dark for hours. The pigments, though, must be protected against contact with water or moisture, and so they are generally used only on dials (since they are protected by the crystal) and not on bezels. Super-LumiNova is the current market leader for luminous watch dials.