A dial will not have a "SWISS", "Swiss made", or "Swiss" marking without some type of lume. Earliest uses of this marking was in 1960 when Radium was applied and because of it's radioactive properties, they felt that marking the dial would give persons in and out of the watch an idea of it's toxicity. I've found this to be true more times than not, but I'm open to all additional information or edits to this statement. Here to learn!
Best,
Thomas
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