Corning Gorilla Glass is the surface for most typical cellphones.
How it’s made: 
The glass is manufactured by incubation in a bath of hot potassium solution. Sodium ions in the glass are exchanged with larger, heavier potassium ions. This results in compressed, chemically strengthened glass. It’s actually a refinement of old technology that dates back to the 1960s, and similar techniques have been used to alter the optical properties of glass.
How it’s branded: