Max, what a superb set of tumblers. Congratulations. They are "Golden Shoji" - Imperial's No. 104. The full range is shown in the Imperial Glass Collector's reprint of the 66A Catalog, dating from the 1960s. There were several sizes of tumblers, as well as a large "hospitality bowl" and two vases. Most magnificent of all was the Sake bottle and cap, plus tiny 2 oz sake tumblers.
The Imperial Collector's Encyclopedia Vol II says that the range was sold through the B. Altman department stores in the New York City area. In the gold-decorated range were a few other fabulous patterns with names like "Sekai Ichi" and Sortijas de Oro". A splendid "Golden Shoji" decanter is illustrated in the encyclopedia.
Should you sell them? Well, I can't even guess at a value (not my area of expertise or experience). The best I can say is that the small glass is shown at $12- 15 in Vol III of the encyclopedia.
If it were my decision I'd hang onto them. They are fabulous. So striking and lovely. Imperial was a great glass company and to have a perfect 1960s set like that is wonderful (especially to have found it in the UK!) They have the IG trademark on too - and are so deliciously typical of the era. Perhaps you could see if you could track down the decanter - or maybe even that Sake bottle. But that's just all my opinion, of course. Hopefully others will be able to advise you with more expertise re. whether to sell or not.