You can identify it using the product code. It is printed on the SIM tray (7 characters long, starts with 059). Or if the SIM tray has been changed, you can go into Settings -> About product and scan the data matrix. It contains the IMEI and product code. Once you have the product code, google it and you'll find which variant it is.

Whether it is made in Finland or China is printed also on the SIM tray and on the box (compare whether the IMEI on the sticker on the box matches that of the phone). Btw. the sticker on the box also states which color the phone is.

The fake N9s that I have seen don't even look like the real ones, neither the housing, nor the SW. And they come in a completely different box. So if the box and the SW seem original, then the only "fake" thing can be the changed housing.