There has been a good deal of debate about the strength and durability of the glass front and back plates on the new iPhone 4. I have to admit, I worry that this doubles the chances that I will scratch, crack or break my iPhone 4. Others feel that the iPhone 4 glass will be exceptionally durable with one person even mentioning that the glass will be bullet proof, similar to the glass on military tanks. I am not that optimistic.

Apple talked about the iPhone 4 face/back glass properties in their promo video:

"We developed a custom glass that’s comparable in strength to sapphire crystal but about 30 times harder than plastic. This glass is not only used on the front of the phone but on the back as well."

Sapphire has a rating of 9 on the Mohs scale of mineral hardness, which is quite strong. Diamond (the strongest mineral) has a rating of 10. That being said, even a diamond is not shatterproof. If hit with a hammer a diamond will smash to dust. It can also chip or be damaged from a drop on the floor.

We've seen other chemically treated screens before, like Corning's Gorilla Glass, that promise very high levels of durability. Yes, there is a video of the iPhone 4 glass being bent about 20 degrees, and that is quite impressive. Though once the glass is assembled onto the iPhone 4 aluminum frame, when is this attribute ever going to be needed? If I drop the iPhone 4 on my tiled floor, its cute bending trick is completely useless to me.

iFixyouri state that they had their hands on iPhone 4 faceplates (no the whole phone, no the internal parts, just the faceplate). It's unknown if what they had represents the final production version of the glass, but they decided to drop test it anyway, face down, on a hard floor from 3.5 ft. After three drops the purported iPhone 4 glass shattered. They also claimed that the iPhone 4 has a design flaw which will cause it to be more prone to glass damage. This flaw is that the glass actually sits above the aluminum bezel as opposed to the iPhone 3G, which has the glass almost flush to the aluminum and is hence more protected by it.

If the iPhone 4 glass were shatterproof, wouldn't Apple have said so? Wouldn't Apple have demonstrated that in their video? We watched the glass bending, why not see it being struck or dropped and not breaking? (Perhaps even better yet we would have seen Steve pick up a AK47 unleash a round or two on the iPhone 4 and then gingerly pick it up dust it off and say, “now folks that’s magic.”)

Perhaps this glass is strong, perhaps stronger than any of the iPhones in production but shatterproof?

What do you expect from Apple's new glass? Have at it in the comments.