Transparent aluminum oxide (TAlOx), a real material despite its sci-fi name, is incredibly hard and resistant to scratches, making it perfect for protective coatings on electronics, optical sensors, and solar panels. On the sci-fi show Star Trek, it is even used for starship windows and spacefaring aquariums.
So invisible jets (with wondrous pilots) when?
(Or do we just wait for pollution to turn the rain acidic like this?)