not having seen giallo in the flesh, I turned to Barry Skelcher's books for information, and he does appear to have investigated the uranium content of this colour, in some detail. Compared to Q'sIW, which is a pale straw cream, giallo is a strong attractive shade of custard - Manley shows examples of both, side by side, and the difference is pronounced. Giallo, like aesthetic green and some blanc-de-lait, did once fetch big dollars, especially in the dolphin bowl shape - whether they do still I don't know.
Could be my imagination, but from the few pieces I've had, the detail produced, in Q'sIW, by the mould, always looks more crisp and well defined than in other colours or types of Sowerby glass.
Somewhere I have several pieces of what I think are Sowerby's rubine, which according to Raymond Slack was a deep red translucent glass, which the factory introduced in 1882 - is this your "rich transparent ruby" Fred??
Of course, it may well have been a colour the factory continued for many years - am sure I ran down the pattern in Glen's CD catalogue - which is how I knew my pieces were Sowerby.
Used to see the odd piece of rubine up until year or two back, but not seen any for a while.
I thought that prior to about 1920, this sort of red could be achieved (in pressed glass only I'm speaking of) by the inclusion of gold (colloidal) - so was this rubine produced with gold (I wouldn't have thought so), or was the colourant copper?
sorry, can't think what any of this has to do with Roy's u. chambersticks