What PVD coating actually is.
PVD stands for Physical Vapour Deposition. The part goes into a sealed chamber, the air is pumped out, and a solid metal such as titanium or zirconium is vaporised and driven onto the steel surface.
The colour is not paint and it is not a plated layer sitting on top. It bonds to the steel itself, a few microns thick, which is why it does not peel, flake or wash off.