It's a fazzoletto--handkerchief--vase originally produced by Venini. Your vase has a nice flow to it, which is typical of a good Venini, but the yellow doesn't seem quite right. However, they were made in a wide range of colours. If it is Venini, it will be signed, acid etched. in fact. The signature can be hard to see (I have one where I can see the writing only on some days), so look carefully.
Other companies copied Venini, both in Murano (Salviati did a lot), and almost anywhere where glass was made. The base is a key element. There's no extra glass in A Venini or Salviati base, both of which are slightly concave so the the vase stands on its rim. The Venini has a polished pontil, whereas the Salviati can be quite rough. If the bottom is flat and clear gas, look elsewhere for a maker.
If you want a more definite opinion, add picture of the base. Last thought: it looks a little heavy for a Venini. Is the glass thick or thin and is it cased (covered in clear glass)?
David