Tulip shaped heavy glass vase

I recently purchased this wonderful vase and am wondering what decade it is from and if it is perhaps from a specific brand/maker. It is incredibly heavy and very special shaped. I first had a hunch that it might also be a decanter, but it doesn't work so well pouring liquid out after all. Therefore, I would stick with my vase guess. (The drops at the bottom of the vase are not in the glass, but from pouring water out.)

The facts:
very heavy and thick glass
about 22 cm high
transparent, very slightly green shimmering glass
no signature/sticker