Along witth others, I have now had the two strange weights in my hands.
What was equally odd, when I first noticed it, was that under Shortwave UV they fluoresced differently. One was "Silver Grey" and the other "Muddy Grey". This suggests to me that maybe they were made out of different pots or at different times. That would be consistent with a regular run of such items, with the eventual pairing up for sales purposes being done later.
But if these were a regular production run, how come the books etc. don't show examples? Perhaps only the more usual versions of "pull up" (or Devil's Fire) designs have been regarded as interesting enough for publication?
What I do find very interesting is that the shiny pieces of mica (?) embedded in the white ceramic mix, as seen quite clearly in Ray's photos, appears to be a smooth gold colour with very little bubbling over the surface. This is a feature that ought to be traceable to a place or time of making, but as yet, I have not seen the same anywhere else.
For now, I think that it is quite likely that this pair was made in France, as mantel ornaments, but Belgium could be a possibility.