I recently bought a Falconnier catalog in German
, dated 1900, and put it online. (I'm working on an English translation). It shows these blocks, or at least the full-size one (this is a half-brick) for use in curved walls, domes, etc:
Looks like the location of the pastille is incorporated into the design, instead of being hidden as in the other patterns, ala bull's-eye panes of crown glass.
The catalog lists four basic styles, and fancy colors "yellow", green
and opal (milkglass). Green I have seen, and yellow usually means amber, presumably including this darker brown shade, and there's a milkglass one in the Swiss National museum, but blue
! Cobalt maybe, or cornflower (which is just light cobalt). Oo la la
, must find one!