The essential points relating to the details of the "5-spout vases" in this discussion made me think. I have an amberina version of this design, which I bought, when I first started getting into coloured glass, as an example of interesting form and colouring. It reminded of the very old Tulip Vases, which were often pottery etc. rather than glass. As with so many of my "old" coloured glass items, I had never found a convincing attribution for this one.
And then this message happened.
Mine is not of the best quality, having what I call a "not-too-tidy" foot, an unfinished pontil area, several small bubbles especially in the "spouts", some sharp edges and some other roughness. The rigaree around all the openings is applied and not formed out of the main body or spout. This sounds to be a method of making similar to Javier's example - and maybe that is the usual way of working a rigaree. The ends of the spouts (and their rigaree) are each squashed in their own individual way - none are round. For the top rim, where the rigaree is applied, there is a definte internal ridge in parts but it is not noticeable to the touch around all of the inner rim.
I believe that touch is essential when examing or analysing items as it can reveal so much more than just a visual appraisal. By feeling (as far as I could) inside the spout openings, I was able to discover additional roughness, sharp edges and a couple of small burst air bubbles at the surface. This added extra information to what I already saw as "less than perfect" working of various parts. With all the information I was able to make a considered decision on whether to buy it and whether to discuss a lower price with the seller.
Here are a few pics of mine - which I think may well not be a Murano item - but??
Full view ... flash photo, shows the amberina shading and also highlights some of the lack of neatness in parts. The dark splodges to the rear of the neck portion are simply magnified areas of accumulated dirt behind the ridges where the spouts are attached.
The not-too-well formed foot - flash photo. This is a cropped image which allows the shape of the foot to be seen. It seems to have been formed by pressing a tool into the edge at more-or-less regular intervals. Note also that "age wear" is visible in parts but in fact there is not as much as I would expect for something with a lot of age. (But, of course, an item of any age may not always have been subject to regular handling or movement across a surface, so "little wear" can not be taken alone when assessing the age.)
One of the spouts - no flash. Without flash, the inner surface of the spout is clearly seen to have substantial roughness. It also highlights well the form of the rigaree, which is not the neatest I have ever seen!
The upper half - flash photo. This shows (or is inteded to show) the ribbing in the neck and shoudler of the vase. In some lighting, the ribbing is virtually invisible. It is most obvious on the inner surface when felt with the fingers - the outside is almost smooth.
As I say, I am not suggesting this is Murano but it may be useful for comparsion to other examples of this style of vase and perhaps it could help in deciding whether another is, or is not, Murano?
Edited to add ...Sorry, forgot to include dimensions. It's 15.5cm (6 1/8 inch) high, 16.5cm (6 1/2 inch) from centres of opposite spouts, 7.5cm (3 inch) outer diameter of rigaree at rim and more-or-less 10cm (4 inch) diameter of foot, which is aprrox 1cm (3/8 inch) thick.