Glass mosaic ribbed bowl

Translucent deep purple and opaque white.
Vertical rim with rounded and slightly uneven top edge; plain, vertical band around top of side, then bulging outward before curving in sharply to small concave bottom.
On interior, two concentric grooves around outer edge of bottom and small, broader circle at center; on exterior, twenty-eight prominent vertical ribs, with rounded tops, tapering downward and extending onto bottom.
Broken and repaired, with two large holes in rim and top of side and one small chip in rim; pinprick and a few larger bubbles; pitting, dulling, and faint iridescence.
Rotary grinding marks on interior and on band around top of exterior.

Ribbed bowls were a very common and popular type of early Roman cast tableware. Examples have been found right across the Roman world and even beyond. Those in mosaic glass like this one were intended to resemble luxury vessels carved out of semiprecious stone such as banded agate.