From scuffgate.net (I wouldn't try this!)
"Making scratches less visible on the iPhone 5S is tricky. If a deep nick or scratch is found on the chamfered edge of the phone, such as when the phone is dropped on concrete and lands on its edge, there will often be small burrs in the metal. Burrs are bits of metal which have been displaced and rise above the surface of the phone. They catch the light and stand out, and can also snag on clothing. If there are burrs on the edge of the phone, you can carefully file them down using a needle file."
Yeah, like I'm gonna get a needle file to my iPhone! Get a case!
Sent from from my iPhone 5