This was as close as I could find on ebay; presumably you've searched there? Perhaps this dealer could help you i.d. it. Antique-Onyx-Marble-Cloisonne-Table-Lamp This one popped up on pinterest, was listed on ebay for 149, but says it's out of stock. No way to know if it actually sold for that. Yours looks much finer than either of these examples. This dealer has many vintage lamps for sale. You might also contact them: https://www.ebay.com/usr/sunzza

Google 'fishbone lamp" and see if any are close enough. That shade, however, you might have to make with duct tape. :P

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?

You will never find that glass again, circa 1990's, you need to measure the "fitter" size at the top or take that piece with you to a lighting showroom, they have glass supply catalogs and can try to get you something that fits. How did it hold on to the fixture? I will tell you an all glass replacement will cost you tho.