Chanced upon this video on youtube. This video shows how GT Advanced Technologies made Sapphire screen for our smartphone.
Apple has contracted GT Advanced Technologies for the production of screen for their iPhone, iPad and maybe iWatch product series. See GT’s announcement here
Advantage
– hard (Last I know, it is only one-tier below diamond. Correct me if I am wrong) and almost “unscratchable”
Disadvantage
– More expensive and heavier than Gorilla Glass (this is what our phone screen made of)
– Sapphire is 67% heavier than Gorilla Glass
A pocketnow.com production.