Although I havn't found anywhere on the net to back this up, I have bought 2 tubes of this style of lipstick and seen many listings for others. HOWEVER, every once in a while I see a tube that can't possibly be real, especially in FIG, which I guess is very popular/rare and discontinued. Its mainly common sense, but have a look at the details and decide for yourself if you are bidding on the real thing...
This is how the case SHOULD LOOK! It should have 1. ALTERNATE BLACK AND SHINY BLUE SURFACES 2. GOLD EDGES 3. ONLY SAY DIOR, NOT CHRISTIAN DIOR.
Although this is a fuzzy image it shows how the BOX SHOULD LOOK! Notice how it is textured and metallic with a black label. Also, every new box of lipstick should come with a piece of paper inside with a Dior world signup form. ON THE TOP OF THE CASE THERE SHOULD BE A "CD".
AND NOW... THE FAKES!
THESE ARE SERIOUSLY FAKE! No gold lines.... all nasty navy blue instead of shiny blue & black... no CD on the top... says Christian Dior instead of just Dior.
Good effort, but there is still no CD on the top and it says Christian Dior, also, that box looks suspect, maybe its just old packaging?
Christian Dior! No Gold Lines! And that box is pretty non-shiny/textured. If this isn't fake, its too old to be good anymore!
All faces of the case are blue, no black ones. Christian Dior, no CD on the top.
I'm sure there are lots of other things, like numbers, embossing etc, but these are the super-easy obvious ones. Also, real Dior lipstick smells good, it smells like a classy woman, if it smells like anything else, its probably not real! Hope this helps!