Nice writeup on cup coins of the byzantine empire. http://www.coinweek.com/featured-news/bert-byzantine-coins-become-cup-shaped/
very interesting, thanks for posting mat. i immediately thought of these two coins i have , both alexius iii sb2011-2013 (not sure exactly). i wonder if the obverse of this coin was struck dead center one time, note the strong center but weak periphery..there is supposed to be some legend...maybe just worn, but fits the single strike on a lower die with greater curvature idea... here is the reverse, this coin (sorry for bad pic), i call the cyclops jesus...what a weird look. but note the strong legend in the left and right fields. i wonder if this one was "miss-rocked" when double struck? here is the reverse...note the strange double head on one of the figures..you see that every so often on these things.
One of these coins turned up on the "Pawn Stars" television show a while back. Episode title "Cold Hard Cash", first broadcast on the History Channel on November 14, 2013. http://www.cointalk.org/threads/byzantine-coin-on-pawn-stars-tonight.238714 The coin was identified by David Vagi of NGC Ancients as a coin of Emperor Constantine IX, AD 1033-1055.
Th US Mint did not even have look back to ancient coins. Earlier in the 21st century, two other mints made similarly shaped pieces ... Christian