I've been saying this since it was first announced on rumour blogs. Saphire is well known for being brittle due to it's hardness, so it makes a terrible choice for phones, especially given how much drama there was over the iphone screen smashings when they first came out. This is why some tool watches (such as pro dive watches and the world famous Omega Speedmaster Pros used in space made a point of NOT using saphire due to the fact they had to be super tough).
A few of my watches sapphire Crystal on them, and they are insanely scratch resistant, but also pretty strong when it comes to knocks. I've ****ted them off metal door handles running through a door a few times and they have stood up fine, but then we're talking about a 3-4 mm thick lens. Something as thin as an untreated phone face would crack pretty much instantly when dropped.
So this is most likely to be used for the watches instead.
Unless they have some super sneaky new technique of laminating it , but even then the sapphire would HAVE to be the outside facing layer for the scratch resistancey to work. But even with a very tough laminated layer that is resistant to breaking I think saphire would have more drawbacks than advantages on a device that can be dropped.
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The surface area is also smaller, which means fewer possible points of failure.
Exactly. I've had some full force running arm swinging impact on some of my watches that have saphire lenses onto granite surface edges (ie rock hard point shiz) and door handles and they've not so much as scratched let alone broken. But this is because they are between 2-5 mm thick - something that is out of the question for a phone where you are probably talking tenths of a millimetre in thickness... hence totally unsuitable for phone use.
However having said that, IF they are releasing a phone with a back face that looks as horrendous as the 'leaked' images that are out there then they've obviously lost the plot so who knows