[cjensen]

Using an extremely expensive ultra-thin high-resolution touch-sensitive easily-scratched display as a scale is a pretty terrible idea. If Apple allows the app and someone weighs tiny diamonds on the screen, whose fault is it that the display is scratched? Ordinary people may not understand how the Mohs hardness scale works. Ordinary people may not be accurate judges of whether or not something is too heavy to place on a phone without damaging it. Cute hack, but too many unintended consequences in the real world.

[matt4077]

RTA! Any object would have to be in a spoon (or something similar). And even diamonds on the screen wouldn't scratch it unless you applied pressure. At which point you don't deserve a scratch-free screen (but can buy one with those diamonds).