(I've just tried posting a reply but a photo was too big, trying again.) I hope these photos will show enough detail to enable someone to identify this vase. The rim is polished smooth on the upper surface but there is a small outer edge which is also polished but very nibbled and a little sharp. I'm wondering if the damage was caused by the vase being enclosed at some point in a metal framework, although this seems a bit unlikely for something so small. I took the surface photo with a flash and the vase was transformed into a wondrously different, multi-coloured object, but unfortunately in normal light is just a dull green! I hope you can see what I mean about the surface looking greasy, with horizontal smears as if wiped with an oily cloth.
Thank you all for taking the time to look at this little object; it's not valuable but it is unusual (to me) and I'm hoping to learn from it.