... earth with HRA90, only after diamond with HRA100, so it won't give way to the abrasion that comes with daily use the ... chopping, such as bones and fishbone, so except for that, you can use ceramic knives for frozen meat, vegetables, fruit, sashimi ... the worlddiamond(100), so you do not need to grind it at all as long as you do not drop it, do not chop or ...