Hi Tim,
Well, this is the definitive proof that Jallas indeed succeeded to F Darne.
I don't know either what the Rhombus is about except that it is a tradesman's mark and not an official proof mark.
The 5 grade stamps are double FDs which no doubt are for Francisque Darne. There is also a half erased tradesman mark on the lump which seems to be Gxxet. The AE is also unknown.
The barrels seem to be monoblocked. I thought Francisque did not do that, but Jallas did.
Best regards,
WC-