Hello,
Thank you very much for your help.
I've been searching all over the net for days.
I think you're definately in the right direction,
because I found a white vase that looks exactly like it.
See link:
http://www.cesonline.cz/arl-ces/cs/detail-ces_us_cat-psb0001757-24-Sklo-Riedel/(In the little square pictures, you have to scroll... it's number 11 of 29)
This one matches on all fronts. The rim, the foot, the transparency.
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But... that was in my search for Josef Riedel.
Then I found this article with a whole family tree.
If I got it right.
The white vase saying JOSEF RIEDEL 1850-1860.
But Josef Riedel wasn't alive back then.
The one who was in charge of the Riedel company was: Franz Xaver Anton.
See link:
http://antique-marks.com/josef-riedel.htmlUnfortunately my search ended there.
Could find anything suitable with this one.