Bowl

During the Roman Imperial period (27 B.C. - A.D. 312), the popularity of elite objects sculpted from colorful stones such as agate and onyx led to the development of a market in glass replicas. These affordable alternatives were cast or blown from multi-colored canes of glass and imitated expensive natural stones. Here, an ancient craftsman has created an abstract version of agate using brown and white glass.
To make the bowl, the artist heated a rod of multicolored glass and laid the molten glass onto a flat surface, spiraling it into the center in a serpentine pattern. While heating in a kiln, the glass would fuse slowly--each curve melding into the next--until it became one large, colorful disk. After brief cooling, the disk was placed atop a hemispherical mold and heated again, until it slumped into a bowl shape. In the final step, the completed bowl entered an annealing oven to cool slowly, a process that kept the glass from shattering.