Thanks for your reply and advice - I have had your site bookmarked for some time as a valuable resource - many thanks.
Note the size variations based on the amount of glass picked up but wondered if there were any clear signs that help to identify copies - does the base
look different for example?
Clear signs to identify copies from the original Holmegaard Gulvvaser (dk) Floor-vases (uk) not to my knowledge, they are blown in a wooden mould and I do not think that leaves a special base. Think the best may is to look at the proportions between body and neck both thickness and length - Too narrow, short or too long neck to a thick body or too thin, too short or too long a body can indicate someting could be wrong.
The transparent ones would be the lightest ones they mostly is one layer of glass, the heavy ones would be the ones with opal glass on the inside often covered with a color f.ex red and sometimes covered with a third layer of clear glass on the outside.
Think the best way is to compare to a photo of a reference vase a put two photos side by side to compare and they have to look alike, body, neck, top finish and body/base ending, this apply for all sizes.
Have often seen the round colored glass item but on top of the Gulvvaser, but they have noting to do with the Gulvvase series and have never been produced for the vases, instead they are, or the one that is Holmegaard, from the "Dekorationskugler" Decorations Balls you can find them under art glass press letter D and find Dekorationskugler and go to the subpage.
Do not think you will be in doubt when holding the Holmegaard Gulvvase in your hand.