Sapphire iPhone 6 Concept
The iPhone 6 screen maybe covered with Sapphire. This is a strong material that is hard to scratch. Apple invested a large amount to secure access to one of the premier Sapphire producers in the U.S. and it looks like the companies are planning to use this material in an new iPhone this fall.
This iPhone 6 concept takes things a step further, covering the entire phone in Sapphire. With a stronger, scratch resistant material Apple could wrap the whole phone in this instead of using aluminum on the back.
Sapphire also could allow easier configuration of antennas that wouldn't need to go through aluminum, which is more challenging to penetrate and why the iPhone 5s back is two tone with aluminum and glass.
This retro style throws back to the iPhone 4s' glass back, but is updated to feature curved edges and Touch ID. This concept also comes from Martin Hajek.