To get our Cinderella Grey marble tumbled effect, tiles with a straight edge are put into a tumbling machine.  Think of it as a big shaker filled with gravel or ceramic pieces.  The tumbled either vibrates or rotates and after a certain amount of time (and a number of broken tiles) the edges of the tiles are rounded out. Tumbled finish for Cinderella grey stone is a very common way to finish natural stone tiles.  Rounded, imperfect edges are a great complement to the other natural characteristics of stone.