Hello all,

During my constant perusal of all things straight razor related, I have come across this discoloration on various blades.
Name: Blade Etching.jpg Views: 319 Size: 76.3 KB
I was wondering what this process is called. It doesn't look like rust or pitting (but I can't be sure), and I have yet to see patina develop in a pattern like that. When I see this should I not be concerned as it is easily buffed out, or should I run for the hills?

I am just trying to train my eye when it comes to what are acceptable vs fatal flaws. Any input would be greatly appreciated.