A little bit out of my comfort zone, this.
It's a beautiful miniature opaline drinking glass, just 42mm tall and 38mm across (1.65" x 1.49" in old money) with dented sides. The gather was rolled in gold leaf before blowing, which would have resulted in a crackled surface - unfortunately most of this has rubbed off, but it has left a pitted surface behind where it once was, and also there is gold leaf trapped under remnants of glass from the snapped-off punty to the base, which shows it wasn't applied later.
The glass is very light and fairly coarse, with quite a few small bubbles and pieces of frit. the circumference of the rim is also very uneven
Absolutely no idea of who/when/what, but I suspect pre-C20... I just don't know by how much.
Apologies for the poor photos - not had time to set my lighting up today.