What are these cups original purpose?

The lamp cups on this base are interesting at best. I see no way that a shade would fit inside the cups shown, or a flat ledge for a shade to fit onto. Could these be cups designed for use without a shade? They appear to be a very similar cut pattern to match the base, but if they did not originally come with the base, then what are these two pieces? The lamp is ebay item number 191739234098 so have a look and post back your thoughts.
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It is very curious that the turned down lip of the cups happens to be wide enough to pass over the bracket arms, and the curve appears to match that of the bend in the brass arm. It sure seems like they might have been made to fit. Interesting...

I agree that they fit the brass bracket very well, but it doesn't look like they could hold a Clarke shade or dome. I was wondering if any one had ever seen something similar used in a sweet meat tray or something made of cut crystal. I don't know who ended up with the lamp, but I would be interested in getting more information on the cups.