Following Apple's adoption of sapphire crystal as a strong and durable covering for the rear cameras on the iPhone 5 and fifth-generation iPod touch late last year, rumors of expanded uses for the material have gained some traction. Back in March, we covered a report suggesting that sapphire could see wider adoption as coverings for displays on mobile devices, and just last week a sketchy rumor claimed that Apple is planning to use a sapphire-covered capacitive home button with integrated fingerprint sensor for the iPhone 5S. Amid these discussions of the potential of sa