Constantine XI Paeleologus (AD 1448-1453). Silver stavraton (6.62 gm). Constantinople. 

IC - XC, nimbate bust of Christ facing, holding book of Gospels, 
double dotted border.
KWNCTATINOC DECPOTH CO PALEOLOG, QYXAPOTH BACILYC POMEON in
two lines around nimbate, crowned bust of Constantine XI facing. 

DO 1787. Bendall. "The Coinage of Constantine XI" (RN 6, 33 [1991], pp. 134-142), 91. 
Extremely rare. 
Some light encrustation. Areas of striking weakness as is typical with this emergency coinage, otherwise good very fine

Ex Christov Family Collection (Ira & Larry Goldberg Auction 53, 
26 May 2009, lot 2420).

No coins of Constantine XI were known to exist until a single 
specimen was identified by Simon Bendall in the mid 1980s. 
In 1991, the discovery of a small hoard brought a handful of 
further pieces to light. These were examples of the silver 
stavraton, the standard coinage of the late Byzantine realm, 
and its fractions, attributed to the last Emperor by the legend KWNCT PAL. Hastily struck and of crude design, the pieces are 
tangible evidence of how far the Byzantine Empire had fallen 
since the heyday of Justinian nine centuries earlier.
Estimated Value: $ 20,000

With permission of Freeman & Sear, Manhattan Sale III, Jan. 2012. 
Lot 235. Sold for $22,500