hello - and welcome to the GMB..........sorry that no one has yet responded to your request - the reason being that it's not a general policy on this board to discuss values. Regret I know nothing of your light shade, although by the looks of things you appear to know at least the maker and approximate age, and can only suggest that you search ebay, auction house records or the general antiques trade, for some guide to a commercial value. You may be asking for re-sale reasons or possibly insurance purposes - although you don't say.
The value of anything is very much a personal thing - some pieces have a greater or lesser value depending on which side of the pond you might be - not sure where on the globe you are. You might contact a dealer in deco light fittings/shades, or someone who deals in domestic wares from that period.
It's not that we try to avoid the subject of shades - just, as I say, that values are too much of a subjective matter to have any hard and fast rules. Try ebay with a reserve perhaps, and see what happens.