The two sections of pigmented glass at the top and the bottom of the phone add a pleasant effect, and the sapphire glass is meant to be thoroughly durable, to complement the Gorilla Glass on the front.
Apple knows consumers get furious when they drop and iPhone, and is clearly seeking to stop the smashes before they happen with a tougher exterior - although it seems the anodised black version is pretty prone to scratching, with a number of users mentioning chipping on the darker hue.
Phil Schiller, Apple’s Senior Vice President of Marketing, reportedly replied to an email from a user pointing out that aluminium will scratch and chip in natural use - and we’re also hearing that white iPhone 5 models are being returned through flaking as well.