Apple’s sapphire display failed a scratch test using sandpaper

The purported iPhone 6 sapphire display panel came off worse in an encounter with a sheet of sandpaper in a new video test, ending hopes the new screen tech would be completely scratch-proof. After taking a knife and keys to the display with no negative impact, YouTuber Marques Brownlee decided to get serious with some rather coarse sandpaper, in his latest post. Compared with the Gorilla Glass iPhone 5S display, the iPhone 6 emerged from the battle in better shape, showing the new material is indeed tougher, but by no means invulnerable. That led Brownlee to the conclusion the display is not pure sapphire, which is higher on the Mohs scale of hardness than the sandpaper used in the test. Pure sapphire, which has a hardness of 9 out of 10 on the scale, would not have been scathed by garnet sandpaper, which gets a 7 out of 10 rating.

In a video posted to YouTube late Friday, a part purported to be Apple’s “iPhone 6” cover glass was again exposed to a torture test, this time failing to resist scratches from garnet sandpaper, a material softer than sapphire. As seen in the above screenshot, the part supposedly bound for Apple’s iPhone 6 shows surface scratches after being rubbed by garnet sandpaper, suggesting the glass is not made of sapphire. In the video, YouTuber Marques Brownlee also shows the cover glass failing to resist scratches from emery sandpaper, which is much harder than garnet. Brownlee goes on to explain the Mohs scale of relative hardness, noting a material with a higher rating cannot be scratched by one assigned a lower number. For example, sapphire — rated 9 out of 10 on the Mohs scale — cannot be scratched by garnet, which is a 7. Emery is a mixture of corundum and magnetite and is assigned an 8 on the Mohs scale. The only mineral harder than sapphire, itself a form of corundum, is diamond with a relative hardness of 10 on the Mohs scale. Further proving his point, Brownlee takes the same sandpaper to the iPhone 5s, known to sport a screen made from Corning’s Gorilla Glass. While the display area is easily scratched, the sapphire-covered Touch ID home button comes out unscathed. With this latest test, it appears the alleged 4.7-inch iPhone 6 part is not made of sapphire as many have speculated, and Brownlee himself stated as fact in a previous video.