A Montblanc ballpoint into which a Parker refill fits and on which the black separators between the cap rings are missing is unambiguously a counterfeit; further indications are inconsistent proportions and untidily worked cap rings. With the case, material quality and workmanship speak for authenticity; older models from the 1980s are regular. Trade in counterfeits is forbidden; buyers can insist on reversal and, in case of difficulties, turn to the eBay forums or the trust and safety area there.