We’re sure that most of you guys are aware that the iPhone’s home button is concave, meaning that it curves inwards. However according to Kuo’s recent notes, he suggests that the iPhone 5S could have a convex home button that is sapphire-covered due to the fact that the fingerprint scanning technology is placed under it and needs a bit more space, which a concave home button would not have been able to provide.
The reason behind the choice of material, sapphire, is also because since the home button is convex, it could be more prone to being scratched, thus sapphire would be a harder material compared to plastic. Kuo has been pretty accurate when it comes to his Apple-related predictions in the past, so perhaps this is a rumor we might not be as quick to disregard, but until we hear the official announcement which is rumored for 10th September, take it with a grain of salt for now.