Update.
I'm really delighted to say that my RYD vase is heading back 'home' to the glass designer's son Sven, who has kindly given me permission to share the following information.
The vase was designed by Sölve Carlsson. Carlsson designed many pieces and outsourced the production to different glassworks, which is why his name is not known - and was not employed by any glassworks. All the glass was sold under the name "GLASET, Sweden" - his own retail chain.
Sven has the original drawing of this vase and dates it to approximately 1965-69. He also owns one in turquoise in two different sizes, and in grey.
The glassworks had the same name as the village and was closed down sometime around 1970. Today, the most well known products out of RYD are boats with the name RYD.
I do hope Sven looks in on us