I use diamond plates to flatten my whetstones mostly, because masochism. They're also great on blades. You wanna look for DMT / Dia-Sharp. All the big online

I use diamond plates to flatten my whetstones mostly, because masochism. They're also great on blades. You wanna look for DMT / Dia-Sharp. All the big online knife shops should have you covered here (epicurean edge, etc)