Think sapphire watch crystals are scratch-proof? Think again.

Sapphire ranks 9 out of 10 on the Mohs hardness scale, making it extremely resistant to scratches.

But scratch-resistant doesn't mean scratch-proof.

And here's something even more surprising:

Hardness doesn't mean a crystal is unbreakable. Sapphire can still chip or crack from an impact.

A small detail every watch enthusiast should know.