Kratzfestes Mineralglas mit Antireflexions- und Saphirbeschichtung: Das Glas der Uhr ist mit einer Antireflexionsschicht versehen um auch bei ungünstigem Lichteinfall eine hohe Ablesbarkeit zu gewährleisten. Die Saphirbeschichtung sorgt für eine größere Kratzunempfindlichkeit als es bei normalen Mineralgläsern der Fall ist.
Commercial jargon unique to German watchmakers, or perhaps to German advertising copywriters. Here is a thread on UhrForum:Scratch resistant mineral glass with an anti-reflective/sapphire coating: the watch crystal has an anti-reflective coating to ensure high legibility even under unfavorable lighting. Sapphire coating ensures higher scratch resistance than is normally the case with mineral glass.
So for the present, sapphire watch crystals yes, sapphire-coated watch crystals no. But in Germany, sapphire-coating is an advertising slogan that takes a licking and keeps on ticking.I don’t doubt over time there could be some breakthroughs with sapphire and new coating processes could make it possible to use as a screen on a smartphone. However, from the research I did, it does not appear it could happen any time soon. Plus, sapphire’s less then flexible and brittle nature suggests, as least to me, that using it in large screen smartphones would still be difficult even if they were able to coat it in a way to keep the screen from splintering.