There is some very useful information recently detailed in the below link regarding the attributed designer of these vases. I gather this design has just recently been officially attributed to Erkkitapio Siiroinen, as detailed in the catalogue published in 2012 for the exhibition of Erkkitapio's works. Many thanks to 'PX' for posting this information.
http://www.glassmessages.com/index.php/topic,38114.msg281987.html#msg281987