If you are not familiar with Stellas, I doubt that there is any one thing to look for Doug. Luke may know of something?
It would be easy to also fake the warranty stickers that Shimano apply for example. The domestic Japanese Stellas all have a serial number on the seat, but that's not the case with the export models, so that will not help either.
I would say your best bet is to assume it is a fake and to get that confirmed by an authorised Shimano dealer. I am sure you can figure out the nearest one to where you live by contacting Shimano Australia (for example). I would guess you may need to do something like that anyway to make your claim?