I have told the seller it is Murano (and so has a friend of mine). He got a very patronising reply, I got a polite but dismissive reply as below:
Description: Beautiful double overlay Art glass paperweight features blue cut to white to clear design with multicolored millefiori center. The base has a paper label BIRKS # 2306, otherwise unsigned but attributed to Baccarat - less than a quarter of the Antique paperweights made by Baccarat contain date or signature canes......Dimensions : 2-1/2" x 2-1/2" x by 2-3/8" high. It is in excellent condition, no damage, chips or repairs. This is what I found on a different site. It is a Baccarat Millefiori but thank you very much for the information.
I don't understand the relevance of providing a description of a different paperweight on a different site.
There's none so blind as them that cannot see...