An underline on your dial stands for Tritium!

@ Roberto,

Your dial is from '63, has a underline that says that there is no radium but tritium used on the dial... imho no exception

This is more an exception i give you to think about ;- )
7922 big crown with gilt swiss underline silver text...


Another question that came up, does T mean that tritium is used?
Here a close up from a 6200 small logo with SWISS T print:


@ Claudio