I did have a look on the great-glass site, which got me a link to the Riedel website - but while the mark on my glasses is there, yours isn't.
But it only dates back to '95.
I can't find any other source of glass marks, but I'm pretty useless at that sort of thing.
But the similarities between your glass and mine are really quite outstanding - Riedel is known for top quality stemware.
Is the stem of yours attached in a similar unusual sort of way? The stem on mine is six-sided, where it doesn't have the circular feature, so that is consistent with the six "lines" on the surface of the base, while yours has 4.
I have been told by a chef that you know you're in a top class hotel, if they're using Riedel.
(I wouldn't know - I'm more likely to be found in a campsite than an hotel! But I do have to confess to peering at marks on cutlery and the wine glasses if I am ever out.

)