YouTuber Unbox Therapy has published a video showing several scratch tests for Ion-X glass, the material Apple is using on Apple Watch Sport. The tests were conducted on sample Ion-X material, rather than an actual Apple Watch Sport, and showed the material to handle a key, a knife, and steel wool. It didn't hold up to sandpaper, however, so make sure you don't rub your Apple Watch face with sandpaper. Sapphire will hold up to that sort of beating—or scraping—however, so if you're expecting some nasty run-ins with sandpaper-wielding vandals, or maybe some sort of horrific shop accident, you may want to consider Apple Watch instead of Apple Watch Sport.