The original Starwalker fountain pen is purely a cartridge filler; a Montblanc converter does not fit. Auctions in which a converter is included are therefore very likely fakes. The counterfeit nibs frequently bear the typical 'Iridium Point' inscription instead of a genuine Starwalker nib. Visually, fakes can be spotted by a black (instead of acrylic-clear) snow-cap dome in the gift-box lid, a 'jagged' rather than clean star on the service guide, wrong proportions (e.g. an overly long grip section) and a different number of fine transverse grooves on the barrel — the original has ten milled rings between grip and clip ring. Boheme fakes use the same telltale nibs; the counterfeit packaging is becoming better, which makes detection harder.
Related pages on fountainpen.de:
• Montblanc Bohème — model overview: https://www.fountainpen.de/boheme-en.htm