We live in fear of cracked, scratched, and smashed smartphone screens. Gorilla Glass is tough, but it isn't tough enough--a face-off with concrete or a sharp object can still permanently scar or destroy the screen on a $600 piece of technology. Wouldn't it be great if the surfaces of our screens were carved from impenetrable diamond, rather than fairly penetrable glasses and plastics? Actually, the next best thing may be possible; Technology Review says "Your next smartphone screen may be made of sapphire."
Most kids know that diamond is the hardest natural substance on Earth, but sapphire is nearly as hard. While diamond alone scores a 10 on the Mohs scale of mineral hardness, sapphire scores a nine. Technology Review writes that sapphire is three times harder and three times more scratch resistant than Corning Gorilla Glass. Sapphire is many, many times more scratch resistant than the glass or quartz commonly used in watch faces.
And sapphire can be used as a glass. Apple currently uses a sapphire lens for the iPhone 5 for its thinness and durability. Why not cover a smartphone's entire screen with one of the hardest substances on Earth?
The answer, of course, is cost. But it's not as expensive as you might think. Writes Technology Review: "A Gorilla Glass display costs less than $3, while a sapphire display would cost about $30. But that could fall below $20 in a couple of years thanks to increased competition and improving technology, says Eric Virey, an analyst for the market research firm Yole Développement."
So sapphire currently costs 10 times as much as a Gorilla Glass panel--that's too high a price difference for smartphone makers, but as the prices of other components continue to fall, and sapphire becomes cheaper to produce as a glass, that gulf will narrow. And at some point, sapphire may be worth the price.
There's also a possibility that smartphones can use an incredibly thin layer of sapphire bonded to traditional glass or plastic. That surface coating would still be durable, but wouldn't cost as much as a thicker sapphire sheet. "GT Advanced Technologies, based in Nashua, New Hampshire, is developing a method for making sapphire sheets thinner than a human hair—much thinner than the nearly millimeter-thick glass used now on mobile phones," writes Technology Review.
GT Advanced Technologies estimates prices can come down to only three or four times Gorilla Glass--potentially about $10 per screen. If anything's standing in the way of sapphire screens, it's other technologies being "good enough." Gorilla Glass becomes more scratch resistant every year, but we wouldn't mind having a phone that we can drop onto concrete without seeing spiderweb cracks and a hefty repair bill flash before our eyes.