I hit and dragged a piece of craggy concrete repeatedly against the screen.
What happened? Nothing. There wasn't a crack, scratch, or sign of any pitting, just a tiny amount of concrete fairy dust that wipes away with your thumb.
The thin wafer of reinforced Gorilla Glass (right) wasn't as lucky. Although the chemically strengthened Gorilla Glass wards off cracks, glass isn't indestructible.
Chinese company Zhejiang Shangcheng Science and Technology shaped both the smartphone screen (left) and the jewel with sapphire supplied by GT Advanced Technologies.
Zhejiang Shangcheng Science and Technology showed off a range of possible forms and applications at Mobile World Congress 2013.
It took 16 days to grow this 250-pound block of sapphire. From here, the boule, as it's called, can be shaved, shaped, polished, and sliced into fine wafers.