thank you, remarkable, well found, great spotting.
The Boda vase " filigrani " is very similar in construction though, in the vase, is a cased example; stunning. The lampshade seems " single skin " ( approx 2 mm thick ) and you can feel the filigrani form within the glass. It's not to the usual high quality/purity of glass atypical of Kosta with an area of sooty deposit within the glass and also the rim/mouth is slightly irregular...saying that I have a Kjellmann piece which is a little ropey too!
Re the " fitter rim " it could easily be both a hanging lampshade or even with a grubscrew fitment, fit an angle lamp. It doesn't feel like an oil lamp shade from others I've seen however I'm not an expert on oil lamps.