I wonder if over time the screen of Samsung Galaxy S2 may get scratched? Is it necessary to use a screen protector?
4 Answers
The S2 has Samsung's toughened Gorilla Glass screen, see the videos in this answer to a previous question for attempts to scratch the Gorilla Glass on an original Galaxy S: https://android.stackexchange.com/questions/2756/looking-for-a-robust-android-smartphone/2777#2777
I can say that I've had an original Galaxy S for over a year now, and regularly keep it in a trouser pocket with my house keys, have dropped it a few times, and other slight accidents, and while the back and sides of the cover have scratches and chips on them the screen is still absolutely unmarked.
However what you might want to consider is the fact that the camera lens on the back apparently isn't gorilla glass, see this question Is Samsung Galaxy S II rear camera Gorilla Glass too?
My SGS2 has a scratch. Normal use, probably my keys did it, I assumed the gorilla glass would be safe, but was sorely disappointed! Wish I'd shelled out for protection!
It is very tough but not magic, I do have a very tiny scratch on mine I have no idea how it got there.
The only way to scratch something is with a substance that is harder than it is, the Mohs scale is used to show the hardness of materials.
I have read that non-oxidized aluminum according to the Mohs hardness scale has a hardness of 2.75, Gorilla Glass is estimated to be about 7.5 but aluminum oxide, aluminum will get a coating it's like rust on iron but this is aluminum, the aluminum oxide has a hardness of 9. Aluminum oxide is better known as corundum Mohs 9 but high quality versions are called ruby and sapphire.
So if you have old oxidized aluminum car or house keys maybe some coins or whatever they will probably scratch a Gorilla Glass screen since they are harder than it.
Just got mine a few weeks ago. I don't think you'll need a screen protector but at the same time if you put your phone in the same pocket as your keys or even spare change, you're asking for trouble