Thanks for all kind replies. There are two or three orb-shaped pieces in the same vein on the net, all attributed (maybe falsely) to Murano. I am not totally convinced mine is Chinese, although there's a chance it is, due to not just high quality but also artistic merit (and to a tiny extent, existence of base wear). If it were Chinese, it would be mass-produced and there's no evidence of this form anywhere. Anyhow, in response to question, here is closeup of neck and surface.