On the octagonal safety pens the size number — 2 or 4, for instance — appears both on the hard-rubber knob at the end of the barrel and on the gold nib; short and long versions were made. Whether the overlay is solid gold is revealed by the hallmark: if it carries no fineness mark such as 585, it is gold plate rather than gold.
The cap is the key to attributing an overlay to its maker. One of the facets of an original Montblanc overlay is engraved with the old Montblanc signature and the mountain motif in the centre. If that is missing and the cap lip instead carries a marking such as “Montblanc 18 k.r.”, collectors take the overlay to be of Italian manufacture and not made by Montblanc itself. A fitted clip also deserves a close look: if its shape does not match the pattern of the overlay, it has almost certainly been added later.
Discolouration and greying of the hard rubber, particularly at the end of the barrel, are the rule on these pens and can be dealt with professionally. The mechanical condition — above all the spindle of the extension mechanism and the seal — can only be judged with the pen in hand, never from photographs. Properly restored, such a safety pen remains well worth collecting even with a later clip, though the price should be correspondingly lower.