Well, it's really not based on anything very solid - the combination of this sort of colours was popular in Germany in the 60s - 70s, and that shape doesn't rule it out. Wiedmann did some pieces for Gral glas that sort of have a similar feel, but I can't find a match to this shape, so it's pure speculation. He did usually sign these sort of pieces, though, so perhaps if you check the remnant of the sig...
Astrid