On a fake Montblanc Bohème Solitaire "Je t'aime" Sterling Silver the typical counterfeit nib stamped "Iridium Point Germany" or "Iridium Point Paris" is immediately visible when opened. In a size comparison the fake is larger than the original. The clip stone on this model should be heart-shaped, but the fake carries a stone resembling the regular Bohème pens. The breather hole also differs: on the original Je t'aime Sterling Silver it is heart-shaped rather than round. The spaces between the rings are flat on the original, while the fake shows ugly notches. At the front of the section the fake has a deep notch that is shallower on the original. The thread at the rear part is plastic on the fake, metal on the original. Under the clip the original carries a "Pix" engraving missing on the fake; the clip itself on the counterfeit is simply bent and looks cheap. Initial identification points are therefore the nib, the clip and the typical notches.
Related pages on fountainpen.de:
• Montblanc Bohème — model overview: https://www.fountainpen.de/boheme-en.htm