I can't seem to find my original post on this which would have been back in 2001 or thereabouts. However there have been a number of posts since then of confirmed Murano pieces with polished pontils.
I have only ever found that one piece but a friend with a large Murano collection had several and Laura and Javier, both Murano specialists, agree that polished politils do not, in themselves, discount a confident Murano identification. However nor do they indicate any particular maker.
My own piece is unusual in that it is clear glass but I have found pieces with the exact same bubble work and hotworked manipulation in colours and which I have no doubts about.
I have personally come to the conclusion that it was done on those odd occasions when the crack off from the pontil rod left a a deeply indented scar, too deep to be polished out to the normal mirror polished flat base.
This reminds me of one other I had of a generic type with crackled (blown out) silver foils, universally accepted as Murano, which had a perfectly circular polished "dish" with the remainder of a deep scar still there in the middle.
The types of base finish to be wary of, in Murano-looking and other types of glass are:
1) Irregularly shaped "dish"
2) Unpolished or badly / partly polished "dish"
3) Unpolished or "part" polished flat base (ie not a "mirror" finish)
4) Where the grooves of a smaller instrument (wheel ?) was used to "carve" the dish and these can be discerned on very close inspection. The "dish" itself may still be circular or almost circular, but often oval-ish, skew or even almost a figure of 8 shape.
These would all seem to indicate that the proper tools were not available and/or sloppy workmanship possibly indicative of lower quality, higher volume production but not necessarily. It is only one indication and should be taken alongside others.
I have no doubts that the piece in question is Murano. Gold bullicante on cased ruby is an often seen combination as is the geode form. I am wary of definitively attributing a maker without documentary evidence. Eventhough certain makers have come to be associated with certain styles it's as well to be constantly aware that on Murano, techniques, styles and fashions spread rapidly among the close knit community of maestri & thieir apprentices, bound together by proximity, history, family and community ties as well as profession. See "Murano Magic" for a much more detailed picture.