Here's the background, in my eternal quest to differentiate Murano w8s from others (Chinese, French, US, etc) I know one of the important factors is to look at the base.
I find that many of the "better" (more pristine) flower, scramble, and millefiori Murano pieces have what I call a sliced base. Highly polished, but cut higher on the sphere than what I consider standard. Most paperweights, whether Scottish, US, Chinese, have a relatively small base, keeping the "sphere" as much as possible. What I call the "slice" is cut higher, thereby lessening the "sphere".
I also find Murano pieces with highly polished smaller, more standard bases, but still flat.
Then there are the pieces that have what I call "edged" or "ledged" bases. Highly polished, flat around the perimeter for 1/4" -1/2", then softly concave, though still highly polished.
And of course there are the pieces with what I call the standard base, small, keeping the "sphere" intact, but not highly polished, and often not perfectly round. For a while I assumed that if the base wasn't perfectly round, and if not highly polished, then it wasn't Murano, but I've found these with Murano stickers, so there went that theory.
I feel comfortable saying any w8 with the "slice" bottom is Murano, at least I've never found one that wasn't. Is that base style emblematic of one specific factory, or is it wide spread on Murano.
I find most of the pieces with the "ledged/edged" base have Murano labels, so I'm feeling comfy with those as well.
So to recap -
"Sliced" base, highly polished - Murano for sure
"Edged" base, highly polished - Most likely Murano
"regular" base, highly polished - Most likely Murano
"regular" base, NOT highly polished - Most likely NOT Murano (with some exceptions).
Am I on the right track? Or am I just making logical leaps, that are incorrect?