I couldn't afford the diamond plates, so I lapped it just now with 600 grit wet sandpaper on top of my kitchen counter. I was surprised at how fast the pencil marks went away and the grain of the stone really pops out, it looks like a cross-cut of oak-wood. As to if its perfectly flat? I went through 3 sheets on the yellow side and 2 sheets on the purple side. Also, chamfered the sides.