This is an unusual decanter for a few reasons....first, the volume isn't large. I can see it be used for a fine liquor or something - especially if the color was interesting.  Next, the stopper is open as if it were a tasting glass.  It's an interesting form and has a little heft to it is the base is a solid bit of glass or crystal.

This decanter is in good vintage condition. It needs cleaning. There are some scratches on base from shelving. Please examine photos!  It stands 11 1/2" tall and is 3 1/4" across at the base. 

Please feel free to ask questions.  Thanks.