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.
Glen