Taking my courage in both hands and enlisting the aid of FreeTran to turn my English question into German, I emailed the seller and asked if there was a maker's name and/or country on the box. This is his reply just in: "warde sagen firma a. masserini- made in italy!" - the company name says A Masserini, Made in Italy.
Now we need to know who A Masserini is/are... I can't find a mention in Ivo's Glass Fact File, but did find a completed listing on eBay Australia for a different design which stated A Masserini, Milano, Italy. Ivo, are they a part of the Bormioli group?
Or has anyone else heard of them before? (Googling for Masserini Milan brings up various companies, none of whom appear to be glassmakers.)