[jmount]

Or just saphire (Al2O3).

[hinkley]

Fancy watches still use sapphire “glass” displays right?

[musicale]

I recall complaints (on youtube?) that Apple's sapphire glass formulation on the Apple watch can be scratched by pure sapphire, but presumably it trades off some scratch resistance for greater impact resistance, though it's probably still more brittle than regular gorilla glass.

[jakzurr]

Samsung Note-3 had tiny sapphire cover over main camera lens.