The suegiro 20k really picks up where the nani 12 leaves off. If the edge off the 12k is worthy, then the 20k will take it one step further. There are various natural stones that with practice can do what you need to do and with smoother imo results than the suehiro. But they are not a cake walk, it will require time and expense as you will spend as much if not more on the jnat and naguras than the suehiro.