History indicates that glass has been in use since the Stone Age. Around 7500 BCE glass in its natural form, obsidian, was utilized to fashion tools. Detailed descriptions on glass-blowing techniques were documented as early as 1500 BCE in Egypt. The Egyptians used glass to glaze pottery before it was fired.

Natural glass is of many kinds: obsidian is glass formed by volcanic eruptions, when masses of naturally occurring silica fuse with intense heat to form glass that is hard, shiny, opaque, and either black, red, or green; tektites and Libyan desert glass are created by meteoritic impacts with the earth or moon; and fulgurites are a kind of glass created by lightning when it strikes sand containing minerals that comprise glass.

Early methods of making glass objects were cumbersome and tedious. Casting, core forming, or cutting techniques were time-consuming and so glass was a luxury item as precious as gold. The discovery of glass blowing in the Eastern Mediterranean region in the first century BCE revolutionized glassmaking, and soon many parts of Europe, especially Venice, were renowned for glass objects of use and decoration. Since then, glass has found many uses in the making of household objects, architectural panes, scientific and industrial products, in the field of medicine and health, and as expressions of art.

The glass we use today is man-made and fashioned from silica, calcium oxide, and sodium carbonate or potash. Variations in glass are then obtained by using additives like lead to create lead crystal or flint glass; boron to make unbreakable heat-resistant glass; thorium oxide to make lenses; and iron to make glass that absorbs infrared energy. Beautiful colors are obtained by including metals and metal oxides. Manganese lends an iridescent amethyst shade, selenium gives red, cobalt blue, tin oxide and antimony produce white, copper oxide gives a turquoise hue, and nickel makes violet or even black. Artisans and manufacturers experimented with different additives to produce a wide range of glass.

What Pliny wrote in his Natural History,