Narrow resting surface; a raised ring round the center of the underside. A groove at the bottom of the upper and the lower wall. Glazed inside and out. Reserved: resting surface, underside within raised ring, with a glazed circle and central dot, and upper groove. Center of floor fired red from stacking.

Three very similar, P 16485 G 18:1-M; P 24162 Q 15:2; P 24259 O-R 7-10. P 12639 is small, diam. 0.061, with less attention paid to detail: groove not reserved, underside reserved, no raised ring. There are two of this date which are not black glazed, having a smooth finish: P 6627, no raised ring beneath; and P 15054 N 21:7, rim fragment. There is a similar example in the British Museum, 64. 10-7. 1759 (F 185) of the late 5th century.