I have the platinum model, and I have zero scratches on the camera.  I have kept mine in a case, but I just got a screen protector.  Thus far, the front and camera survived scratch and mark free some time with my tungsten carbide wedding ring.
When I do the dishes in the sink or do something unpleasant, I will put my wedding ring in my pocket, usually my phone pocket because I hate it when it get's stuck on my keys.  One day, I left my ring and phone in the same pocket (no case this day no screen protector yet).  I was out doing yard work with them together, chasing my son, threw it in the hamper until my wife was doing laundry and pull them both out..
Not a scratch or mark despite several hours with a LOT of contact.  Tungsten Carbide Steel is stronger than surgical steel.  I have ground down handles with it, scratched all measures of surfaces from concrete to steel, paint, whatever.  I figure I have a fair amount of luck here, but I am still very pleased with the quality of the phone.
EDIT:  You know that feeling you get when you replay to a post on page 2 that's like two weeks old...yeah, feeling that!