Hi - welcome to the GMB

This type of glass décor might be trying to suggest some degree of antiquity, but equally might have been made recently, and failing any useful response here it might be a sensible safety move to get these checked by an electrician. From what I can see in your pix, there appear to be eyelets around the interior of the top opening of the shade - this might suggest these things were intended to hang on chains or similar - but I'm really only guessing - and it may be that there is some additional part to the shade that currently is missing.
They might well have been intended for desk lamps.
Would agree the appearance of the panels does suggest a slag or marbled type of glass construction, but looks can be deceptive on the screen - are the panels fully opaque, or is there some degree of translucence - the answer might provide a suggestion as to how these shades might be used. Sorry this is unhelpful - fingers crossed someone better informed might have more positive information for you.
Regret we don't discuss values on the GMB - whether ballpark of other - which probably seems unhelpful in view of the many dollar values you guys on your side of the pond discuss freqently. People here are amateurs and not professional appraisers of objet d'art, and our suggestion is always to search for similar items listed on both on-line and physical auctions. ............ failing which a call to antiques centres might be useful.
