Ten FAQs About Apple's Sapphire Screen

With the impending launch of iPhone 6 just a few days away, we take a look back at what made this gadget interesting in the first place: It is a scratch- and smash-proof device thanks to super-tough sapphire glass.

Previous iPhone models are already using sapphire glass in small quantities – it’s what protects the iPhone’s camera and covers its TouchID fingerprint sensor – but with the iPhone 6 Apple is expected to use thin layers of sapphire glass for the whole display.

Unlike Gorilla Glass, which is found in most modern smartphones, synthetic sapphire is supposed to be much tougher, but it’s also trickier to make.

1. What is sapphire glass?
   Sapphire glass is made from discs of crystallised aluminium oxide. It’s produced using very high temperatures, cut with diamond-coated saws and polished to make glass.
   
   The only material that's harder than sapphire is diamond — it can't be scratched by any other substance.
2. Is it completely indestructible?
   No, it is not. While sapphire is almost entirely scratch-proof, it's still susceptible to cracks.
3. Where is it made?
   Apple’s sapphire glass will be made in Arizona by GT Advanced Technologies.
4. What’s so great about it?
   It’s thin, light and really, really tough. It can resist being stabbed and scraped, it can survive falls onto concrete without being scratched, let alone smashed, and it doesn’t chip. You can still break it, but it’s likely to withstand everyday lumps and bumps much better than current smartphone displays can.
5. What makes it different from Gorilla Glass?
   Both Corning Gorilla Glass and sapphire have separate advantages when it comes to preventing damage. Gorilla Glass is slightly flexible, which makes it more durable against cracks. While sapphire is more brittle, its ability to fend off scratches can prevent cracks from occurring.
6. Is sapphire screen bad for outdoor viewing?
   Another fun fact about sapphire: it's more reflective than glass, which means it'll be difficult to see your phone's screen in sunny or bright conditions. A sapphire screen will reflect almost twice as much light as ordinary glass.
   
   It all boils down to the basic principles of optics. Not only is glass less reflective than sapphire, it also transmits more light. Glass transmits roughly 90 percent of light, while sapphire's transmission rate is in the low 80s.
7. Will it cost more?
   According to the Wall Street Journal, Gorilla Glass displays cost around £1.80 to make, but the same screen made with sapphire glass comes in at around £9.60. It’s also more difficult to make in big numbers, so inefficiencies could drive the price up further. Industry rumors suggest that Apple might only put the sapphire screens in its most expensive iPhone 6 models.
8. Why it's so expensive to make sapphire?
   One of the primary reasons we don't see many smartphones with sapphire screens is because it's too expensive to product in large quantities. This isn't because the material itself is difficult to grow; it's the preparation process involved.
   
   Currently, sapphire is produced in large, bulk pieces. These giant pieces then have to be chopped and sliced down into plates.
9. Is sapphire glass used anywhere else?
   Yes. Luxury phone firm Vertu uses sapphire glass in its extremely expensive Vertu Ti smartphones, and Kyocera’s Brigadier uses a sapphire screen as part of its almost indestructible shell. Other smartphone firms including Samsung and LG have reportedly reached out to sapphire glass companies with a view to using sapphire in their own devices.
10. Will sapphire glass end up in the iWatch?
    That’s what the rumor sites say. Thinner, lighter, tougher glass makes a lot of sense in a small device such as a smartwatch, so if Apple can make it work on a big phone it’s likely to want it in the iWatch too.