Northwoods21it depends on your phone, and which material you got:poly carbonate probably wont scratch it, however the edge on the money clip might if you get that. aluminum is probably safe too, however the titanium is likely to scratch your phone glass. not entirely sure of the mohs hardness level of carbon fiber, but most modern phones scratch at a 6 so anything softer is unlikely to scratch the screen
Most metals are softer than glass this is why I ask.