“The fracture toughness of sapphire should be around 4 times greater than Gorilla Glass – about 3 MPa-m0.5 versus 0.7 MPa-m0.5, respectively.”

Sapphire is often used for windows/viewports on pressure chambers. At least in that capacity, it functions much better than regular glass.

not much more, and more brittle than gorilla glass which isn't regular 'ole glass IMO. Way way more scratch resistant though, so again IMO, totally worth the tradeoff if price isn't a factor.

For larger displays being shatterproof seems like the more important problem to me. Scratches are already hardly a problem with glass (I get the impression that tiny sharp rocks are pretty much the only thing that can cause problems in the environment those displays are usually in, so to avoid most scratches one has only to avoid laying the display face-first on some dirty/hard surface and sliding it around) and even then a few scratches are not as much a problem as a shattered screen. Shattering is much more fatal to the device and it often only takes one or two drops and the glass shatters.

Being absolutely scratch resistant is a desirable property for a camera lens (which is also much, much smaller and thus much less likely to shatter). It doesn’t seem like such a desirable property and good tradeoff for screens, at least not as long it isn’t as shatterproof as the best glass.

In many ways I tend to think that scratches are a solved problem on mobile devices. Current glass is good enough. Shattering is not. (I’m not gentle to my devices but my 18 month old iPad has practically no scratches. Some are faintly visible if you look at it from certain weird angles. However, the glass of my previous iPad did shatter from a 1 meter or so fall of the edge of the device on tiles. Also, I see people using phones with shattered screens all the time. It seems to be a quite common occurrence.)

Yeah, improving scratch-resistance further would be awesome, but only if there is no trade-off with being shatterproof.

If scratch resistance could be greater it would be very useful. My screen on my older phone has some deep scratches from keys in my pocket - something I now avoid - and hard labour. Smashing concrete, heavy lifting etc when you have a phone in your pocket is brutal on phones. Its a terrible environment for a phone, but I try to get stuff done even when on call. I have checked the screen on a builder I know too, and he has scratches too.

What phone is that? Maybe it has a plastic screen, those get scratched easily.

In my experience metal is typically much too soft to cause any damage to the glass. If anything can cause damage it’s sand and the like (but it has to really press up against the screen). So, yeah, in an environment with a lot of that stuff glass screens will get scratched. However, it’s not like that’s a common environment for phones to be in.

Iphone 4. My new phone will be treated a little better!