Feature:
add two tabs to JEI's recipe viewer: one showing all of the grindstone polishing recipes that can be performed with either grindstone, and one that shows all the polishing recipes that require a non-depleted diamond grindstone.

Additional info:
this would really help with seeing what all can be polished on the grindstone and which items need a non-depleted diamond grindstone specifically. this becomes even more important in modpacks where new polishing recipes have been added.
in terms of layout, the recipe displays in these tabs could be similar to those of Create's sandpaper polishing or Sully's Mod's grindstone polishing: the input item on the left, the output item on the right, and the relevant grindstone model or a custom 2d sprite of the grindstone in the middle. for extra clarity, hovering over the grindstone picture in the middle should inform the player that

• they need to right click an item onto the grindstone to polish it
• shift right clicking polishes the entire held stack
• if the diamond grindstone is required, that it needs to not be depleted