Have found this about what I believe is the symbol on your piece - the Byzantine double-headed eagle
How similar did this look to the Russian double-headed eagle, the supposed descendant of the Paleologues eagle?
Some background for it: Michael VIII Paleologue adopted this symbol after he had reconquered Constantinople from the Crusaders in 1261. It represented looking towards the East (Asia Minor, traditional power center of the Byzantine-government in exile after the IVth Crusade) and theWest (newly reconquered land in Europe.)
The double-headed eagle had in the two centuries of Paleologue rule become identified not just with the dynasty but with the Empire itself and, more generally, with institutions and cultural ideas outside the Byzantine Empire that still remained centered on Constantinople.
Most obvious of these is the Greek Orthodox Church, centered in theory in Istanbul to this day, and so it is not surprising that the Church would use the flag.
Less obvious is the reason for its use by the Russians... In 1453 a flood of Byzantine churchmen and nobles fleeing the Ottomans ended up in Moscow, center of the last free major Orthodox polity. This more or less coincided with the adoption of the title of czar (Caesar, or Emperor) by the former Princes of Suzdal who had been ruling from Moscow and had united much of the Russian-speaking world. Moscow began to be referred to as "the Third Rome" (Constantinople being the second), and the Czars saw themselves as successors in the Orthodox world to the Byzantine emperors. Thus the adoption of the double-headed eagle by them. This is the flag of the Greek Orthodox Church
http://www.flags-of-the-world.net/images/g/gr_ortdx.gif
