Special marking is possible using femtosecond lasers.
Black marking
This method uses short pulse lasers to achieve high visibility black coloration while minimizing thermal damage to the material surface and not altering the material's properties.
Color Processing (Structural Color)
Coloration through light interference by forming a periodic structure on the surface.
Coloring Processing
Coloration can be achieved by interference of light with the oxide film formed on the metal surface.