Nice. Two-piece transpositions are definitely cool.
It's tough to date this one. There's no known BROOKFIELD embossed version, and this style appears in their 1912 catalog and maybe earlier ones. From what we can tell, there doesn't seem to have been a wholesale shift from the BROOKFIELD embossing to just a B, as once had been thought. Just guessing by appearance of the glass, it looks better-made than Brookfield's very late products made in their last couple years, so for this piece, maybe 1910-1915 or so.