I believe your piece is indeed Murano, as olecanalantiques has showed some beautiful examples of Murano Millefiori Italian glass it is not the only style, type produced, There are many factories which produce glass on the island of Murano which has been Italy's main glass-making center since 1291. That was the year all the furnaces were restricted to this island to prevent Venice from going up in a blaze. A few glass factories: Domus Vetri d'Arte , Sent Guglielmo (which I believe is the maker of your piece as they produced enameled & hand painted glass) , Carlo Moretti and Barovier e Toso.