Matt Witt

Any good quality silver polish would be "safe" for this. Go to a shop selling antique silver and they will have any number of polishes, cloths, etc. Of course, there is always a debate as to whether you want to polish it or not. Some say yes, some say no, but it won't effect the value either way. Just dont polish it every week, or with a polish meant for anything other than silver (brass polishes, for instance, are fairly abrasive by comparison) and it will do quite well. A good polish will have chemicals that will help the case hold its shine longer, thereby avoiding the need to repolish as often, should you decide to shine it up in the first place. The enamel won't be harmed by a quality, commercially available, silver polish either.

As to the original post, someone noted that they wished they made repros of (signed?) cigarette cases. They do, they usually just don't tell you when they sell it to you. I have pointed out a couple silver items over the years that are purported to be WW1 silver cases,flasks, etc., that (curiously) carry hallmarks from the 1920's, 30's or even the 40's. Hallmarks are your easiest defenses to fraud. Every stamp means something: national origin, town of manufacture, silver content, silversmith, and date. English marks are the most comprehensive, but the German marks can be very helpful too.

And at the risk of stating the obvious, no pilot ever "signed" an inscribed case. The jeweler did. Someone would give the jeweler a sample signature for his use. I could easily do the same today. At the time, they were popular presentation items, gifts, etc. (Do you remember everyone signing everyone else's high school annual?) I don't know how much time lag might have been involved in getting one of these done; maybe a few weeks? A month or so? But clearly events could sometimes overtake these. Might some of these even have been made as memorials for the family (the late pilot's survivors)? Certainly that was done with cups and platters. As silver became harder to find, and casualties mounted, I suspect these cases would have been thought of as a good option, both cost wise, availability wise, and as a piece of personalty reminiscent of the lost family member. (This last is sheer speculation however.)