History of glass
Glass remained a luxury material, and the disasters that overtook Late Bronze Age civilizations seem to have brought glass-making to a halt. It picked up again in its former sites, Syria and Cyprus, in the 9th century BC, when the techniques for making colorless glass were discovered. The first glassmaking "manual" dates back to ca. 650 BC. Instructions on how to make glass are contained in cuneiform tablets discovered in the library of the Assyrian king Ashurbanipal. In Egypt glass-making did not revive until it was reintroduced in Ptolemaic Alexandria. Core-formed vessels and beads were still widely produced, but other techniques came to the fore with experimentation and technological advancements. During the Hellenistic period many new techniques of glass production were introduced and glass began to be used to make larger pieces, notably table wares. Techniques developed during this period include 'slumping' viscous (but not fully molten) glass over a mould in order to form a dish and 'millefiori' (meaning 'thousand flowers') technique, where canes of multicolored glass were sliced and the slices arranged together and fused in a mould to create a mosaic-like effect. It was also during this period that colorless or decolored glass began to be prized and methods for achieving this effect were investigated more fully.
Gold glass
From at least the 17th century the Roman glasses attracted antiquarian interest and they began to be removed from the catacombs, in a largely disorganized and unrecorded fashion; now only a "handful" remain in their original position in the catacomb walls. The first significant publication on them was by Filippo Buonarroti in 1716, "Osservazioni sopra alcuni frammenti di vasi antichi di vetro ornate di figure trovati nei cimiteri di Roma" ("Observations on some fragments of antique glass vases decorated with figures, found in the cemeteries of Rome"), in which he made the extraordinary, almost proto-Romantic assertion that the aesthetic crudity of early Christian art, often remarked by connoisseurs of Roman arts, had served to intensify the piety of the worshipper, an early expression of feeling for primitive art. After other studies, the Italian Jesuit Raffaele Garrucci published the first illustrated survey in 1858, with an expanded second edition in 1864. In the 19th century a number of imitations, copies and downright forgeries of Roman pieces were made, mostly in Murano off Venice, by firms such as Salviati. The first major public exhibition of these seems to have been at the Exposition Universelle of 1878 in Paris, by Italian firms.