Yeah, as I said. I'd like it to look like the blocks were made out of the very same material. The color could be slightly off, but.. yeah.

And with depth.. I mean the outline. It's a little hard to explain. Take, for example, the Inferno tilesets. It has tiles where there's actual shading and stuff at the border. This creates an illusion of depth, it makes the wall look more three-dimensional.
Also, in the same tileset, you walk on some kind of layer on top of the rock. This also has depth.
However, I'd like for the rock to have a rounder edge... ...I guess I'll have to try again myself if I want to explain this. *sigh*