These end mills have a diamond or diamondlike coating for machining abrasive material, such as carbon fiber, fiberglass, and graphite. Made of solid carbide, they are harder, stronger, and more wear resistant than high-speed steel and cobalt steel for the longest life and best finish. Their extreme hardness means they are brittle, so a highly rigid setup, such as a CNC machine, is necessary to prevent the end mill from breaking. They have a ball end for milling rounded slots, slopes, and contours. All are center cutting, allowing plunge cuts into a surface.

End mills with fewer flutes provide better chip clearance for high-volume, high-speed plunge, slotting, and roughing cuts; end mills with more flutes provide a finer finish and operate with less vibration when run at high speeds.

Diamondlike-carbon (DLC) coated end mills are an economical option for short runs and intermittent use. Diamond-coated end mills are good for long production runs. They run twice as fast as other carbide end mills and last up to 30 times longer.