Montblanc pens are top-of-the-line writing utensils as well as pieces of great craftsmanship. However, sometimes these pens are counterfeited. People who want a Mont Blanc but can't afford one, or have been scammed into thinking they are getting a good deal, may end up with counterfeits. While counterfeits may look almost identical to the real thing, there are specific differences to look for.
Compare the price of the Montblanc pen to the price of the pen in question. If it is hundreds of dollars less than the cost of the real pen, there is a very good chance it is counterfeit.
Measure the pen against the dimensions of a real Montblanc pen. Counterfeits may come within about 1/8 inch of the real pen, so it is important to be precise.
Look at the engraving on the clip of the pen and on the tip. It will be much crisper and more detailed than on the counterfeit, especially the engraving on the tip of the pen. The counterfeits will have just a single, shallow line of script.
Take off the cap of the pen. With the fake pen, it will require more effort than with the authentic Montblanc. The cap will easily come off the real Montblanc pen, but it will not come off on its own.
Look at the feed on the pen, or the part from which the ink flows. On a counterfeit pen, it will be a smooth tank, and on the authentic pen it will be ribbed.
Take out the box and look at the edge of the lid. It will have an Oriental-style engraving on it. The counterfeit boxes will look and feel the same, except for this one detail.