A patina, not wear
The contrast between the light raised areas and dark recesses is created during manufacture. Routine cleaning won’t remove it, though it may fade on areas touched frequently after several years. That’s normal for this type of finish, and many people seek it out.
Care
Use a dry or barely damp cloth. Never use silver polish: it would strip away the patina in the recesses, the very feature that makes this finish appealing.
Coordinating your hardware
To coordinate your furniture, explore other colours of furniture knobs and handles. For a similar period feel, see our antique-style door handles and retro door handles.