Luminova

Often used in the manufacture of contemporary watches Luminova is a  phosphorescent (glow-in-the-dark) pigment which are based on Strontium Oxide Aluminate chemistry. It was invented and developed by NEMOTO & CO. LTD. of Tokyo, Japan

When exposed to light it stores energy and when viewed in dark conditions emits a glow.

It is applied to the hands , indexes and hour markers so that users are able to tell the time in any conditions.
It is a successor to Radium with its dangerous radioactive properties.

More recently Super-Luminova an even stronger version has been developed.