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