How scratch resistant is the Apple Watch Sport's screen?

http://www.theguardian.com/technology/2015/apr/22/apple-watch-sport-screen-scratch-resistant

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The vast majority of Apple Watch sales are expected to be of the cheapest version, the Apple Watch Sport – but just how scratch resistant is its screen?

The Sport’s screen is made from Ion-X glass, unlike the Apple Watch and premium-priced Edition which have sapphire screens.

Sapphire is one of the hardest materials available and is used in the screens of high-end watches from makers such as Rolex and Omega

Most smartwatches are covered with the same hardened glass as smartphone screens. It is softer than sapphire and can be scratched by more materials including keys.

So how scratch resistant is the Sport’s Ion-X glass?

Lewis Hilsenteger from Unbox Therapy, he of bending iPhone 6 Plus fame, claims to have sourced two Ion-X screens from the Apple Watch Sport for testing and found that neither a metal implement such as a key or knife nor steel wool could scratch the screen. Sandpaper, however, did cause heavy scratching.

Sandpaper is typically made from silicate, with different impurities added depending on the hardness or coarseness of the sandpaper. Sandpaper should not be able to scratch sapphire screens, as silica is a softer material than sapphire.

Hardened glass, however, is of a similar hardness to the silicate used in sandpaper and therefore can be scratched.

The test shows that Apple’s Ion-X glass on the Apple Watch Sport will have a similar scratch resistance to smartphone screens, which notoriously can get scratched up just through general use. Whether that’s hard enough for a wrist-borne device remains to be seen.

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