Ingela, thank you for your help you have made my day! :hug:
Of course the engraving Sg stands for Studioglas, I see that now, obvious once you know.
I am not so sure about the 'Strong' engraving, it looks to me like it is made up of 5 letters. At present I would guess that a visitor to the glassworks may have asked for the engraving to be added (name and dates) - maybe the vase was to be a present for a 50th birthday.
The link to the photo gallery of Eric Hoglund glassware is fantastic, I have bookmarked it so I can spend hours gazing wistfully at the images. On page 6 towards the bottom there is a photo which includes two of these vases. :hiclp: I also fell in love with the cast face at the top of page 2 and the cast figure at the bottom of page 3.
So the vase is an Eric Hoglund design which has left me with a small dilemma, I was thinking of selling it but now I think I will have to keep it.