Columbia subject headings:
Harvard subject headings:
Art objects, Byzantine--Congresses.
Art objects, Byzantine.
Art objects, Classical--Congresses.
Art objects, Classical.
Gems, Ancient--Congresses.
Gems, Ancient.
Gems, Byzantine--Congresses.
Gems, Byzantine.
Gems, Classical--Congresses.
Gems, Classical.
Gems--History--Congresses.
Gems--History.
Precious stones--Congresses.
Princeton subject headings:
Gems, Ancient--Congresses.
Gems, Byzantine--Congresses.
Precious stones--Congresses.