Probably 1920's as it's an interesting hybrid - the base has elements of Art Nouveau as does the beaded fringe. The shade is more Art Deco but it also seems to have some Art Nouveau design elements.

Unfortunately the beading is gone and I would suspect it might be expensive to have it replaced.

I have no idea what FMV would be - you would need to find the right buyer - would depend on your location and how you are planning to sell it.

Have you considered hiring an appraiser?

@Helen, Thank you for your reply. I live in Moscow, Russia and I also never tried to sell anything like this. I tried to contact a few antique stores around Moscow, but they haven't answered yet. Trying to find someone who knows about lamps more than me as I know literally nothing at all except the information I surfed through today. :)

I have no idea of what kind of prices these would bring in your area - or whether it is feasible to ship outside of Moscow.

You can try looking for prices on EBAY under Art Deco or Art Nouveau lamps which might give you some idea.