Some people will disagree, some will go ballistic...
Diamonds cut fast and stay flat, they are great for shaping, sharpening blades to a working edge quickly.
They work dry or wet, oil or water, clean or dirty, they just work. Always.
Not much attention nor maintenance required.
Ceramic cut more slowly and wear away. They must be wet, not soaked but constantly wet.
They are great for touching up and finish honing a super sharp edge.
In my opinion they are not for establishing the primary bevel. Too slow.
They can take a sharp blade to the next level of super sharp.
They have to be flattened and cleaned often to keep them in top condition.
I use them only when the highest finish is needed.
But I treat my planes differently from most people.
My only super tuned, super sharp planes are the smoothers. They get honed all the way to 16,000 ceramic.
The scrub plane gets 325-400 grit diamond. Done. Works fine for what it does.
Jointers get 1000 grit diamond and a strop. They need to cut but not polish the wood.
Chisels get various treatment depending on the job at hand.
For rough work 600 is enough.
Fine end grain paring with my finest chisels may go all the way to 16,000.
Which I use and when depends on the work, the wood, my mood, and expediency.
