There's been a lot of talk lately that the iPhone 6 may feature a sapphire glass screen and a new patent filing certainly seems to point in that direction.

The patent is for an oleophobic (anti-smudge) coating that works on sapphire crystal. Apple has been using oleophobic coatings on its screens since the iPhone 3GS as it helps prevent fingerprint smudging, and a patent filing for a sapphire-compatible one suggests Apple is serious about getting sapphire into its screens.

This follows evidence that Apple has invested in machines designed for building sapphire displays and a previous patent filing that shows a sapphire glass equipped iPhone, so the evidence is certainly mounting up.

Ultra strong, ultra expensive

On the other hand there's also been suggestions that the costs are just too high and even if it does happen it might not be good news. Sapphire crystal is super strong which could make it an ideal replacement for Gorilla Glass, but it can also be heavier and lead to dimmer devices and shorter battery life.

Still, whether or not it arrives in time for the iPhone 6 there's enough evidence to suggest that Apple is pretty serious about a sapphire future.

As well as sapphire screens we may see interchangeable camera lenses in the iPhone's future, as another recent Apple patent details a bayonet mount which can be used to fasten different lens types to an iPhone or iPod, though with this being the first mention of it we'd be surprised if it's something we see in the iPhone 6.