Love this Large Blue Vintage Lamp

I fell in love with this lamp and purchased it from an antique store this past weekend. After buying, the gentlemen said that he believes it's an older Robert Sonneman piece - however, he cannot locate on the internet and unsure - stated the sticker (validating authenticity) has possibly fallen off - ?? There is not a signature anywhere and it's quite large - blue measures 21 inches tall. It's vintage and in great condition.

I've searched the internet and am unable to locate who made this -
Does anyone know or have any thoughts regarding?

Thanks in advance!