ORIS with sapphire crystal since 1998
Watch purchased in 1998, ORIS BC3 sapphire crystal glass front and back in a stainless steel case.
After 15 years the front and back glass is unmarked whereas the steel case shows scratches and marks.
However, the glass is actually quite thick to compensate for the fact that it would be too brittle if made too thin. That unfortunately is a trade off with sapphire crystal. It is also heavy.
I think Apple are looking to use a laminate on anything bigger than a watch, or a new form of glass that has shock resistance built into it.
Really 'thin' sapphire crystal is brittle.