Start by reading the first post in this thread (and the rest if you're inclined):viewtopic.php?f=41&t=8567
Since you can't see the inner case back, you can't confirm or deny that it's marked Hamilton. But if it's not marked Hamilton on the outside, then I think you can begin to suspect non-Hamilton jeweler's case. Other than that, you just have to pore over the catalogs just like the rest of us. Even if that is a factory model that shows up in the catalogs, there's nearly 0% likelihood that anybody will recognize it without resorting to methodically scanning the catalogs themselves.