The stone used to polish Tierrafino Stone, is preferably a semi-precious stone, like an agate stone. In all cases the stone must have a hardness of at least 7 out of 10. The harder the better. The stone must lie comfortably in your hand and should have a seemingly flat surface (somewhat rounded), with which polishing is done. Basalt and granite are suitable stones to work with, they can be shaped into, preferebly, oval shapes with rounded edges.