The company stress tested multiple samples of sapphire and Gorilla Glass in a bend fixture. The video gets a bit technical, but the result seems to support the conclusion that sapphire is not a more impact durable material than typically used smartphone glass, though it is certainly harder. In a scratch test using a tungsten carbide scratching mechanism, sapphire was unaffected while gorilla glass and tempered glass suffered deep, visible gashes. In a bending test, uBreakFix showed that though failure strength of the sapphire is about 25% higher than glass, it's unable to bend and absorb impact, which could mean impact cracks and shatters.
"Our conclusion is that sapphire alone will not equate to an unbreakable iPhone, in fact the brittleness of sapphire glass poses significant problems for engineers to overcome, and we have serious doubts that it will outperform Gorilla Glass. But, we can't say if an iPhone 6 with a sapphire screen will be more or less durable overall. Clever engineering and protective features may still create a very durable device regardless of the use of sapphire," said David Reiff, the company's Co-Founder and Vice President.
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