It's sandblasted, not rusticated. There may have been a pit or something on one side, and rather than hiding the straight grain running along the top and birdseye on the smooth side, they only blasted half of it. You can notice the lines running lengthwise that would have made rings if the block would have been oriented as such, as they cascade down the side. Blasting to me enhances the look of some pipes, whereas rustication just covers it up. I have a Cavicchi and J Alan with a similar layout, actually. It's rare I find a partial finish I like, but this one did it for me.