Video: How Apple plans to make its own scratch-proof glass by Philip Elmer-DeWitt @FortuneMagazine November 5, 2013, 7:42 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons FORTUNE — Never heard of GT Advanced Technologies GTAT ? Neither had we before Monday, when the New Hampshire-based crystal manufacturer announced that it had signed a multiyear contract with Apple AAPL to provide sapphire materials in Apple’s new Mesa, AZ, factory. As happens, we now know quite a bit about GT’s technology for growing sapphire “boules,” thanks to the good folks at Pocketnow who visited GT’s Salem, MA, plant in April and videotaped the attached YouTube factory tour. According to GT, iPhone screens made of sapphire could be even more scratch-resistant than the ones that now use Corning’s GLW Gorilla Glass. Thanks to Horace Dediu (@asymco) for the link. See also: First look at Apple’s U.S.-based sapphire crystal glass plant.