From the site:
A ROMAN GLASS GAMING DIE
Circa 2nd Century A.D.
Deep blue-green in color, the large twenty-sided die incised with a distinct symbol on each of its faces
2 1/16 in. (5.2 cm.) wide
Acquired by the current owner’s father in Egypt in the 1920s.
Several polyhedra in various materials with similar symbols are known from the Roman period. Modern scholarship has not yet established the game for which these dice were used.
Also of particular interest to us is that apparently it currently is the property of a Maryland Fine Arts professor. For just $17,925 it looks like you could possess the potential source of the first critical hit…or fumble.
I think we all know what game they were using it for…