Rough Stones
#220
Best for reshaping or repairing chips. Please be aware that the #220-300 grit stones are very abrasive, and therefore will take off a lot of material.
#300
Best used to quickly put an edge on very dull knives. Please be aware that the #220-300 grit stones are very abrasive, and will shave off a lot of material.
Diamond Sharpening Stones
Diamond sharpening stones are primarily used to repair chips. The benefits of using a diamond stone is that the stone will always stay flat. Please be aware that moving and changing from a higher to lower angle while sharpening on a diamond stone will ruin the blade.