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Two Venetian glass products from the 15th century are crystal and lattimo.
Crystal is a material that is particularly transparent, as created by the Venetion Angelo Barovier: its transparency is obtained by using very pure raw materials. http://www.vivarini.it/en/murano-glass
Lattimo is a milky opaque glass which was obtained by adding lime to a mixture of lead and tin. Nowadays calcium and sodium fluoride crystals are added to give it its opaque aspect as the latter are dispersed during cooling.
Another opaque glass product is the so-called “chalcedony”. This glass was made by bringing a mixture of opal and transparent glass fragments to the point of fusion, and afterwards silver nitrate was added to the fused mixture, along with cobalt oxide, potassium bichromate and other salts. Once everything was added the fused mixture was brought to working temperatures and the products created looked like siliceous minerals, or as mentioned chalcedony, which was used as an decorative stone.
Typical products from the 17th century are “avventurina” and “girasole” glass.
Avventurina is a transparent glass in which copper crystals are evenly distributed during the cooling of the fused mixture. It seems that the product was discovered by accident, through an error in the preparation of the mixture. Given the difficulty of creating a shiny metal effect of quality, its creation was considered as the Italian word suggests, an “adventure”, or “gamble”, which is why the product has this name.
Girasole glass is an opaque, translucent glass which was used in making carafes; it was made by using all types of opaque glass and through the addition of substances during the cooling period, they separated drom the glass matrix, with different refractive indices. By adding lead arseniate the glass took on a light blue colour in reflection and light brown or pink when seen in transmitted light.