In 1898, Madame Curie and her husband found the metallic element. The first World War pushed out the development of watch industry because of the large demands of military watches. At the beginning, watchmakers used the mixture of radium and Zinc sulfide as luminant coating of the watch details. The first Submariner Ref.6204 also used this metallic element.
Radium is extremely radioactive element, which does harm to life, so in 1963, Rolex started to apply Tritium. In 1966, Rolex pushed out the Submariner Ref.5513. However, this luminant coating can run for 12 years.
Luminova (Super Luminova)
Famous copy Rolex watches are sturdy and durable, however its luminant function does not. It was the least of perfection, so Rolex was finding better substitutions. Until 1998, it begun to use Luminova supported by Nemoto and Co. Later, Luminova was improved into Super Luminova which has longer lifetime than Tritium.
Never stop improving, Rolex finally designed Chromalight in 2008 which was firstly used in Deepsea and widely used in all the modern watches replica Rolex Submariner. Different with the green rays of Luminova, Chromalight has blue rays.