It's in the shape of a ship's decanter, although it's quite small, but I can't remember seeing a decanter with the spiral around the neck, usually it's individual rings. One by Steuben is shown here:
https://www.replacements.com/crystal-steuben-7912/c/561835It's difficult to tell but yours seems to have quite a lot of wear on the base, perhaps indicating it has some age. I assume the strong manganese glow is produced under 365nm. UV light, this might also indicate age. I can't identify the maker but I wonder if it might be European.