With this green colour of the glass and the seamless copper base I´m quite confident
it is a Driburg Kristall piece dating around 1970. A friend of mine, Mr. Baumann, has a
small collection of them and confirmed the Driburger Glass Museum has some of them
in their exhibition.
He sent me some photos some time ago, but I´m afraid I can´t find them at the moment.
If you send me a copy of the picture I´ll ask him if he remembers this particular shape.