Sapphire is the second strongest material on the planet and has been hyped as an alternative screen cover for smartphones, but at last, Apple chose to use glass which was reinforced using an ion process in the iPhone 6 line. Why?
One problem is design. The trend in smartphone design is to achieve thinner, lighter and bigger at the same time. What we know about sapphire is that it is more than 30% denser than glass and would require a compromise on both fronts for widespread use in phones. Corning, the maker of Gorilla Glass, has shown that it can manufacture glass to be thinner than a sheet of paper and strengthened with a process that makes it more damage resistant. It’s more flexible and can be formed and shaped into the sleek designs you see in the iPhone 6 and others.
Another issue is light and battery life. By far, the number one phone-related complaint from consumers is battery life, so they have to pick up iPhone external battery to keep their devices going on. And one of the biggest drains on battery life is the brightness of the screen. According to Soneira, sapphire screens are intrinsically more difficult to read in bright light and tend to suffer from much higher total reflectance: the 8% reflectance rate on sapphire screens is nearly twice that of glass, and more than 3X higher than the excellent 2.5% reflectance of the iPad Air 2’s display. Therefore, to get the same level of brightness using a sapphire screen requires more energy.
Finally there is the problem of price. Glass is about a tenth the price of sapphire to make – which can mean manufacturers have more budgets to focus on other areas of the device. Also sapphire uses around one hundred times more energy to produce than glass, potentially making it less environmentally friendly. The researched opinion early on was that if Apple did add a sapphire screen to the new iPhone, it would add at least $100 to the base cost. That could be a deal-breaker for mainstream iPhone customers.