IIRC maganese was used by virtually all American glass manufacturers from the 1800s til 1920ish. So I suppose if the glass was dyed purple, it would turn more p

IIRC maganese was used by virtually all American glass manufacturers from the 1800s til 1920ish. So I suppose if the glass was dyed purple, it would turn more purple as it was exposed to UV but only if the glass was manufacturered during that time period.