So that, I think, settles it. St Louis, mid 19th century. There are several other St Louis pieces with arches in this book, none quite the same as Dinah's goblet, but all very similar. We have received more email about the constituents of old glass that made them fluoresce. When irradiated, antique glass with manganese turns deep purple.
Antique glasses are capable of turning many other colors.
It is not known exactly what elements, other than manganese, produce what color changes. Technical journals written on glass irradiation discuss only late 20th century present day glass formulas, not old glass formulas. Thank you Bob for sending us this information. We hope you are still enjoying the Club page. If you would like to tell us a little about yourself or your collection, we'd love to hear.