It is a homage to the Blancpain Fifty Fathoms, one variant of which had that 'no radiations' dial. The 'no radiations' refers to the fact that radium was not used for the dial lume, so meeting some military and commercial specs at the time (mid 1950s). Not sure if Tritium lume was specifically excluded too?

On the Precista version, it is purely decorative of course as it would have superluminova anyway.


(photo from http://www.watchdeco.com)