The tag usually gives it off. The top tag (of the two) says the size, in red, in the upper-left corner. Furthermore, you won't see the little 'R' in a circle. (I forgot what that symbol is called.) Finally, there's a second tag underneath that says (as Renault78law mentioned) that says 'Designed in France', 'Made in Peru', and 'Hecho en Peru'. On the other hand, if it looks plenty real and almost undistguishable...who's going to argue with you? =]