The chip breakers on my Clifton planes are very precisely machined flat at the correct angle. The flat face had microscopic lines in it. I thought I would polish it on a leather hone; big mistake! The tiny rounding of the leading edge was disastrous at collecting chips and my attempt to flatten it on a stone did not go well, I had to replace it!
I have improved Stanley chip breakers successfully in the past with the stone on a glass plate and supporting the rear of the chip breaker on a Teflon block creating the correct angle, then sliding back and forth.
The Clifton level of machining is something else again.