On a 146 from the 1980s, a missing clip engraving is normal; serial numbers were only introduced later. The typical reddish shimmer of the precious resin against the light is a good authenticity feature — if it is missing, that points to a counterfeit. An official, free nib exchange is only possible on new nibs with an invoice; a subsequent nib purchase from Montblanc typically costs at least 100 euros. If applicable, a swap among collectors offers itself. When posting pictures, the size and file-name guidelines of the forum (max. 499 × 499 pixels, 50 KB, no special characters in the file name) are to be observed.