Flashed glass
Flashed glass, or flash glass, is a type of glass created by coating a colorless gather of glass with one or more thin layers of colored glass. This is done by placing a piece of melted glass of one color into another piece of melted glass of a different color and then blowing the glass.
The colored glass can be partly or completely etched away, resulting in colorless spots where the colored glass has been removed.
Flashed glass can be made from various colors of glass. A finished piece of flashed glass appears translucent.