Right now, the cost of employing sapphire glass on a smartphone display might make it too costly to use. In addition, most manufacturers might not be able to contract for a steady supply of the material. Apple is rumored to be using sapphire glass for the Apple iPhone 6, but the tech titan has been building a factory in Mesa, Arizona that will produce the material for its devices.
Apple currently uses sapphire glass on parts of the Apple iPhone 5s that cannot afford to be scratched, such as the rear camera and the Touch ID fingerprint scanner. While Apple is basically saying that it can't trust Gorilla Glass to keep those areas free of scratches, the video below seems to indicate that Gorilla Glass 3 does have some pretty good scratch resistance properties, and at a lower cost to manufacturers.
Earlier this year, Corning responded to all of the talk about sapphire, by listing a number of negatives that using the material can bring. Still, once the price of sapphire glass comes down, it could end up replacing the material used by most manufacturers today.
source: adrianisen via NPU, WMPoweruser