Hello and welcome to the gmb!

I know nothing about really good old expensive glass - it's way out of my league, but my jaw just dropped.
I saw a fabulous and elegant tall vase in an antique shop in Amsterdam many years ago, (when we visited frequently). It was Tiffany, the real thing. Taller and a different shape, but to yours but the same decor.
I used to visit the shop just to drool, twice a year.
Don't get too ecxitewd!
You'll need somebody who knows a lot more than I do to explain why it is or isn't.
It could well be somebody far more recent emulating Tiffany - I'm afraid I can't blow your pics up big enough to see the surface texture clearly.
Well, I hope you're going to cause a stir of some sort here with this vase!

It is fabulous, whatever it is.