The next iteration of the iPhone from Apple Inc. (NASDAQ: AAPL) is expected to use an especially hard type of glass cover that has been promoted (not by Apple) as being scratchproof. Sapphire glass is rated with a hardness of 9 on the Mohs scale, where diamond is 10 (the hardest) and talc is 1 (the softest). A substance with a higher number will scratch anything with a lower one.
Gorilla Glass, which is used as the main glass covering of the iPhone 5s, is believed to have a hardness rating of around 7 as well, but the maker, Corning Inc. (NYSE: GLW), has never released the Mohs scale number for the material. A glass cover that people call sapphire glass and that they believe will be used in the next iPhone was put to the scratch test by a tech blogger who discovered that garnet sandpaper, with a hardness rating of around 7, put scratches both on the Gorilla Glass cover and the so-called sapphire glass cover.
So the glass cover that is expected to cover the iPhone 6 is almost certainly a blend of sapphire and some other type of glass. The cover also bends slightly, which is another giveaway that it is not pure sapphire glass, which is very brittle. The tech blogger who did the scratch test also had no luck trying to break the cover, which likely means the days of the smashed iPhone glass cover are behind all but the most determined road warriors.