The description fits a Slim Line ballpoint. The range was made in the 1970s and 1980s and was the firm's slim, inexpensive everyday model: a slender brushed-steel barrel, gold-coloured clip and push-button, the emblem inlaid at the end of the clip. To change the refill the pen unscrews at the level of the clip mounting; above the thread sits the two-line engraving with the country of origin. Spelling it “MONT BLANC” as two words is usual on pens of this period and no mark of a fake.
The Slim Line sold at the time for between about 15 and 20 DM, putting it among plain everyday pens. Its collector value is correspondingly modest, and examples still turn up frequently today. Fakes are not to be expected in this range, because copying it would never have paid at those prices — pens that come to light are therefore almost always genuine, and remain perfectly usable as sturdy everyday writers.