A video published to YouTube on Tuesday shows a scratch test featuring what is claimed to be an Apple Watch Sport's Ion-X cover glass, a scratch-resistant material whose properties lie somewhere between toughened glass and sapphire.
If the display cover procured by Lewis Hilsenteger of Unbox Therapy is legitimate, it comes constructed from a proprietary ion-impregnated glass Apple has branded Ion-X. While not as durable as sapphire, which is used on Apple Watch and Apple Watch Edition models, Apple says Ion-X is more resistant to wear and tear than hardened substrates typically found on current smartphones.
To create Ion-X material, Apple dips glass into a molten salt bath that transfers smaller sodium ions out of the substrate, filling in the spaces with larger potassium ions. Exposed surfaces become hardened during the process, making it more resilient to scratching and nicks.
As seen in the video, Apple's special glass withstands punishment from a key, knife and steel wool, but fares poorly against two sheets of sandpaper at unspecified grits. The results are comparable to similar products like Corning's Gorilla Glass, itself used on iPhone and iPad models.
Apple's Ion-X glass is thought to be less expensive than sapphire crystal, making it an attractive choice for entry-level Watch versions. In addition, Apple Watch Sport models are being marketed to active users who likely prefer lightweight Ion-X panels to heavy sapphire faces.
Earlier this month, a UK iPhone repair company got their hands on an alleged Apple Watch sapphire panel, which was subsequently stress-tested using sandpaper, keys and even a power drill. Unlike today's results, the sapphire part came out unscathed.