Fracture vs. scratching
Here’s what the site was told:
“Apple confirms the iPhone 7 camera lens is sapphire, and under proper testing conditions achieves the hardness and purity results expected from sapphire.”
Rene Ritchie says that the iPhone camera lens in the video was fracturing instead of scratching at the lower levels on the Mohs Scale of Elemental Hardness.
The scratching of the watch vs. the fracturing of the lens is clearly stated in the video and shown under the microscope.
Fracturing — as opposed to scratching — is what happens when you have something so incredibly thin — unlike the much thicker watch used for comparison — and you apply pressure with no level of control.
You’d have to precisely apply the same level of force, likely to the same thickness of material, to properly do that test.