Gold Glass - Is the term applied to several types of Hellenistic and ancient Roman glass objects decorated with designs cut and/or engraved in gold leaf, which is sandwiched between two fused layers of glass. Hellenistic gold glass was made by sandwiching the decoration between two closely fitting cast, ground, and polished vessels, which were then fused.
The technique was used in Hellenistic times, and Hellenistic examples are generally both more technically ambitious than Roman ones, with wide bowls or drinking cups decorated all round their curved sides in gold glass, and executed with more artistry.
Many Roman gold glasses apparently were made by applying the gold leaf to the surface of an object, reheating it, and inflating a parison against the decorated surface.
Examples of gold glass mosaic tesserae began to be used in domestic mosaics in the 1st century AD, with Rome apparently the first location. They continued to be used throughout the ancient and medieval periods into the modern day. By around 400 gold began to be used as the background colour for Christian religious mosaics, as it was throughout the Byzantine period.