History of glass
The history of glass-making dates back to at least 3600 years ago in Mesopotamia. However, they may have been producing second-rate copies of glass objects from Egypt, where this complex craft originated. Other archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or Egypt. The earliest known glass objects, of the mid second millennium BC, were beads, perhaps initially created as the accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Glass products remained a luxury until the disasters that overtook the late Bronze Age civilizations seemingly brought glass-making to a halt.
Byzantine glass
In the middle Byzantine period, Byzantine glass-makers adopted silver-staining techniques from the Arab world. Silver-stained glass is created by applying a metallic compound, mixed with a "carrier" of clay or ochre to the surface of the glass object, then the glass is fired below the softening point of the glass. This process results in the breakdown of the smeared compound and its transition into the body of the glass object, creating a "stained" effect. Depending on the makeup of the compound and the "carrier" this process can lead to a wide array of colors. While the Arabs began creating silver-stained glass objects in the late eighth century in Egypt, the first Byzantine silver-stained object has been dated to the ninth century. The most common items featuring Byzantine silver-stain are simple glass bracelets, dating from the tenth to thirteenth centuries, and being discovered across the Byzantine world, from Greece to Anatolia. The most famous example of Byzantine silver-staining is the interior inscription of the beautiful San Marco bowl, dated to the "Macedonian Renaissance" of the tenth century. Several fragments of silver-stained window glass have been discovered. Although silver staining was practiced by the Byzantines, silver-stained works were not as ubiquitous in Byzantium as they were to become in late Medieval Europe. However, the widespread use of silver-staining in Byzantium could in part explain the transmission of silver-stain technique from the Arab world to Western Europe.