Handle Protector Plate

[naicidrac]

Hello all,
recently I acquired this Schwab Safe and started cleaning it up. I noticed that the plate was tarnished so I started to polish it to get it back to looking good. I noticed this oval/diamond pattern in the plate started to come off when I was polishing it. What is this pattern for and is there a way to save it? Actually I have already removed some of it as you can see in the attached pictures. I wanted to know if this serves a purpose or is it just cosmetic?

Thanks in advance