Thank you both very much, this is all interesting to know. Just to add, there is a single bubble in the glass, the inside is smooth and the outside textured. Looking at it again after what you chopin-liszt said, I would say it is impressed also there's no seams. Does this sort of bowl have a name or is there a way to find others similar? Searched online for impressed and slumped but can't find anything like it. Not sure about it being Arcoroc as it's so heavy, and from my limited experience those pieces are quite light.