Hi guys! I have a case back of moon watch, do not know how to real or fake? Please look it for me, thanks

 

The caseback is basically genuine, but has been "customized". The original writing on the outer side was ground away in order to be able to engrave an advertisement or dedication or whatever these "20 anos" stand for.

 

I am probably wrong, but it looks like a 20 year service presentation.

 

Interesting if it was factory done.