iphone 5 is made with a level of precision you'd expect form finely crafted watch not a smartphone

http://www.apple.com/iphone/design/

Never before has this degree of fit and finish been applied to a phone. Take the glass inlays on the back of iPhone 5, for instance. During manufacturing, each iPhone 5 aluminum housing is photographed by two high-powered 29MP cameras. A machine then examines the images and compares them against 725 unique inlays to find the most precise match for every single iPhone.
Look at iPhone 5 and you can’t help but notice the exquisite chamfer surrounding the display. A crystalline diamond cuts this beveled edge. It’s what gives iPhone 5 its distinctive lines. Fitting for a phone so brilliant.

Aluminum and Glass Body

The back of iPhone 5 is made of anodized 6000 series aluminum — the same material used in Apple notebooks — with inlays along the top and bottom made of ceramic glass (on the white and silver model) or pigmented glass (on the black and slate model).

Precision-Matched Inlays

During the assembly process, each iPhone 5 aluminum housing is photographed by two high-powered 29MP cameras. A machine then compares the images with 725 uniquely cut inlays to find a precise match.

Sapphire Crystal

Although the surface of the iSight camera is as clear as glass, it’s not made of glass. It’s actually sapphire crystal, whose hardness is second only to diamond on the scale of transparent materials. That means the surface of the lens is far less likely to scratch.

Diamond-Cut Beveled Edge

A crystalline diamond is used to cut the chamfers of iPhone 5. This process gives the beveled edge its beautiful sheen.