Mineral glass is a scratch and impact-resistant glass most commonly used in watchmaking. It has superb reflective properties, strength and clarity and is reasonably priced. It is referred to as "MG" in the watch industry.
Properties of Mineral Glass
Mineral glass gets hardened by a tempering process and is more likely to break than plexiglass. Although this is the case, mineral glass remains more scratch-resistant than plexiglass. Mineral glass crystals are coated in a hard material which makes them less likely to be scratched.
Mineral Glass Production
Mineral glass is a common glass and used in the manufacturing of windows and watch faces. Mineral glass is used in place of sapphire in watchmaking because it is more affordable. It can be very hard to tell the difference between mineral glass and sapphire; one sure way is to perform a scratch test.
Warning
Although it is scratch-resistant, mineral glass is still susceptible to scratches and chips. Mineral glass crystals tend to have a greenish tint to them, and when viewed at an angle, may cause distortion.