Originally Posted by Cizuz
Why did no one point out the Mohs scale DOES NOT say a softer material can not scratch a harder material.
It certainly can, what the Mohs scale measures is resistance or reluctance of one material to scratch another.
Sand paper can scratch diamonds, the thing is it comes down to percentages basically. A 7 vs an 8, an 8 will scratch the 7 95% more than the 7 will scratch the 8, a 10 will scratch a 7 99.99% more than a 7 will scratch a 10.
Those are made up numbers because it really really depends on the materials used, and Mohs scale is actually outdated and quite wrong in a lot of cases. But that's the point, a harder material resists scratching from a softer material. That's all. It does not say a softer material can not scratch a harder material.
That said what really gets me is people expected this to be all sapphire, and that would be horrible. A single sheet of a hard material means it'll be more prone to shattering. The more hard a material, the more brittle.
So to get around this, and what is what you REALLY want is a multiple layer, treated, or different technique. The best screen you can hope for is a sapphire layer, on top of a more flexible layer. That means the sapphire will resist scratching, but being a thin layer allows it to flex with the under layer it's fused to, such as a flexible glass.
This isn't a bad thing, and people in comments are trying to say it is.
A diamond screen would be pretty much the worst screen ever, diamond shatters pretty easily, which is why everytime in a show they show them testing a diamond by hitting it with a hammer is cringe worthy, a real diamond would shatter. Though a diamond screen would be pretty scratch proof(Still can scratch it, just more resistant). That being said the best screen would be a diamond layer on a soft flexible layer.
This bugs me, because all these people arguing have no idea about material science. We use steel because it's a blend of soft, hard, and tensile strength making it a perfect material for building. People want us to use titanium instead, but titanium in most cases would be a worse option then steel due to being harder and more prone to failure.
Material science doesn't come down to best X, it comes down to best X, Y and Z balanced for expected loads, use, and expected failure points.