This is no coating. The hardness if 316l is about 221 HV machined or not. I am a watch collector as well and 316l is a very common steel for watch cases and believe me the tolerances in watchmaking are tighter than in razor production. Long story short, if you want to have 316l scratch resistant you'll have to harden it or put a coating on. Before just telling about different things please be so kind to read the data sheet.Rockwell 6s is made from sintered
It’s density and surface hardness are
lower than billet 316L .
Machining billet 316L ,
especially with low tolerances
-the piece is subjected to higher
levels of work hardening - can
radically affect the surface roughness
of the piece and raise it up to
1500 Vickers ( HV ) .
Thus ,machined 316L razors
-especially those with tight tolerances - have already a surface hardness in
the range 1200-1500 HV .
Thus there’s no actual need for any special coating.
Most coatings ( carburizing ,nitriding & nitrocarburizing ) affect corrosion resistance in negative ways .
They do lower the corrosion resistance
of 316L stainless steel.
It should be noted that sintered 316L has already a lower corrosion resistance than billet 316L .
So applying most of the available
hardening coatings will make
the sintered 316L more
prone to corrosion.