#724 Ohzuku Type 30 XL Hard Mirror Finish 5 Hardness 5 Fineness 1600 grams

Hard mirror finishing stone from Ohzuku mine, not an easy stone to use for inexperienced users, best for razors and knives where hard steel will be worked on, these might not agree with high alloy steels or large carbide alloys. With the use of a nagura, a stone of this hardness and fineness is useful on knives like yanagi or usuba that benefit from a very fine finish on the ura (inside hollow ground side).

This stone might be scratchy at first and will need to be flattened and the face polished with hard tomonagura or hard nagura. 

206x78x39mm 1600 grams