Ivo has a vast knowledge of much European glass, and this piece may well be from the factories he has indicated, but just thought I'd add some comments which might be of interest, showing that similar features were fairly widespread in the latter part of the C19. This glass might have a potentially wider origin than at first thought.
The greyish tint is known to be an indication of the reaction of exposing glass containing manganese to u.v. - too much produces the slightly purple colour seen on some older glass - and use of this as a decolourant was widespread in Europe
The feature of grinding/polishing the underneath of drinking glasses so as to cover almost the entire base can be seen on many drinking glasses - from the period Ivo mentions - and from many sources across Europe.
Assume this piece doesn't have 'hardglas' or VSL stamped anywhere.
Could be wrong but I get the impression that non-British drinking glasses are more likely to be engraved with the intended capacity - in line with Ivo's figures - but that's just my opinion.
As far as the U.K. is concerned, glasses are found occasionally marked with the capacity, as shown in the attached picture of pressed goblet/rummer - this one has the words in relief on the inside
of the bowl - so presumably an 'open shut mould' used rather than a standard plunger process?? I've no idea of factory or its date but thought possibly early C20.
Another feature (although not on this glass) of interest regarding pub/tavern glasses is the official Weights & Measures Verification Nos. found on C20 (mostly) pint and half pint glasses, although can be found on C19 examples.
Seen usually on straight sided glasses - and Sowerby, doubtless amongst many factories were producing this shape around 1885 - 90, and we still use them today. Picture attached showing the typical motif of a crown surmounted by the word PINT and with the Verification No. below - this one I think is for Warwickshire post 1974. In fact the Sowerby catalogue does include an example of a straight sided beer glass showing this motif with a Verification No., so it looks like this factory were licensed with a specific Verification No., although I don't have any further details.
With thanks to Chris Cooper I believe who added this link to the GMB........ http://www.antique-metalware.co.uk/uvnumbers2.asp
So next time you're in a pub and at a lose end, your can enter the No. into your screen and up will pop the town/city from which your glass originated, and some indication of date range - then you can impress your friends.
Obviously an attempt to avoid short measures Uniform Verification Nos. were introduced in 1879, although some sort of system had been in use apparently for a long time before, but needed standardizing. Don't think I've seen a C19 pint or half pint example.
The fact that this piece is without such a mark might suggest non-British or just one of the zillions of glasses that were for private use.
Well worth having a look at the Sowerby CD catalogues to see the massive variation in capacity/shape/design etc. of similar glasses between about 1880 and 1930's............ descriptions such as ...scant half pint - a pony was one seventh of a quart - a nobbler (that's if I can read correctly) being one third of a pint.