I find the whole Horcrux business somewhat dubious. I mean, what exactly happens when a Horcrux is destroyed? Obviously, the object is destroyed, and the spell that binds the particular piece of soul to the object is broken too, but what happens to the soul? I mean, if a body is destroyed, the soul doesn't die, it goes on to afterlife. JKR has established this as a fact in the world she created. So I have a bit of a problem believing that the destruction of an object leads to the detruction of the soul, if even the death of the body doesn't accomplish that.
My point is: When somebody creates a Horcrux, he stores half of his soul in an object, so that when he dies, his soul doesn't go on but remains connected to the half in the object. Now, if the object is destroyed, shouldn't it be the same thing? The part in the object doesn't die but remains connected to the half in the body.
Isn't that the very reason why Horcruxes work in the first place? That a soul only passes on when it's whole? What actually happened to the pieces stored in the diary, the ring etc? Erased? I think the book suggest there's a bit more to it than we might believe.