Thank you all for your input, it is not only reassuring but also fascinating.
This piece is catalogued for 1971 and is 32 cm/12" and a bit in height, so it's a nice sized vase.
Unfortunately the Studio Crystal movement here in Belgium, is often, or is should say always actually, associated with the pieces VSL did later on in the nineties and onwards, during demo's. A little shop was created on the spot and these pieces were sold often as souvenirs to visitors. This vase is not part of that, it was designed by SH for VSL for a specific range. SH was commissioned in 1968/9 to design and create a range of unique pieces by the Galerie Lecuyer in Brussels. They were done at VSL who had nothing to do with it except provide the space rented. I have read that SH needed initially some assistance with the lead glass or crystal, as he had not worked with this before and was done so by Louis Leloup who doesn't need an introduction himself. Several pieces are therfir signed by both artists. Once VSL saw the results, they commissioned SH to create the Eldorado series, which the vase in question is part of.
Unfortunately because of the earlier mentioned stigma, the Eldorado series is not appreciated as it should be and because of that, not much is known about it here. Having said that, SH has been of huge influance for VSL with Harvey Littleton and came back to VSL in '89 and '90 to create two more series if one-offs for VSL. He showed something completely new and helped setting up the workshop at VSL and developing it further, wich lead to the Art & Design series, with several big names associated/collaborated to it.
It is nice to put things back in its place and 'set the record straight' so to speak.