I came across a terrific article by Sebastian Anthony @ ExtremeTech. Sebastian gets into the benefits of sapphire including transparency, it’s toughness and transparency and its resistance to acid and other hard substances.
Sapphire glass, except for its cost, has some incredibly desirable qualities. It’s highly transparent between 150nm (ultraviolet) and 5500nm (far-infrared), much stronger than normal glass, and it’s one of the most scratch-resistant materials in the world — it scores 9 on the Mohs scale, one down from diamond’s 10, and quite a lot tougher than Gorilla Glass’s ~7. Its transparency, plus its very high melting temperature (~2,000C) and high thermal conductivity, make it almost uniquely suited for use in arc lamps, laser tubes, and other extreme use-cases. Oh, it’s highly resistant to acids and other caustic substances, too.
Sebastian also takes the cost component of sapphire head on and refers to a source that said sapphire 3-4x the cost of gorilla glass a year ago. As I know from my research technology changes fast and GT Advanced has been hard at work reducing costs and improving yield to compete with any cover material on the market.
There are two factors here that make Gorilla Glass more desirable than sapphire: cost, and potentially thickness. Back in March 2013, when we first covered GT Advanced Technologies, one analyst said that a smartphone-sized piece of sapphire glass would cost $30. By comparison, the same piece of Gorilla Glass costs $3. In the video above, GT says sapphire glass is around 3-4x more expensive than Gorilla Glass. Corning itself says that sapphire glass isn’t thin enough — though, again in our March 2013 story, it sounded like GT had acquired some technology that would allow for the creation of thin sheets of sapphire glass.
I think more and more people are understanding why Apple is making the switch on the surface to sapphire glass but the truth behind the move to sapphire is more than cover deep.