A glass ball with coloured glass shapes inside

Edo-Kiriko, a traditional cut glass craft in Asakusa, Tokyo, Japan. The glass has two layers, a coloured layer outside a clear layer.

Glass is a hard material that can be made in many shapes. It is usually transparent, but it can also be made in colours. Glass is mainly made of silica; glass made of silica only is called silica glass. It originated in India.

Glass used to make windows and bottles is a specific type called soda-lime glass, composed of about 75% silicon dioxide (SiO₂), sodium oxide (Na₂O) from sodium carbonate (Na₂CO₃), calcium oxide, also called lime (CaO), and several minor additives.