I'll be the voice of discontent, since most advice here, thus far, is to forget it and move on.

If a friend of mine had loaned my daughter a camera and she broke it and then returned it without a word, I'd like to know. As a parent. Something is wrong here. It could be simple ignorance (the damage occurred but wasn't noticed) but it could also be that the child didn't know that it's expected to be returned in the same condition it was loaned in. She may assume this is normal wear and tear. It's sad, but true, how little regard some people, kids or adult, have for material things.

This is an important moment in the child's life. Doing nothing may save your friendship with the family, but someone is getting away with something.

I've said my peace. As a parent, I'd want to know. I would literally be brought to tears if my daughter acted like this.