What a interesting idea:

It might have sound bizarre or purely unbelievable when Mont Blanc launched “fraud proof” ink saying “Only one person will own this ink – You,” but given the reputation of the iconic pen manufacturer you can’t help but trust. Recognized as the icon of writing culture, Mont Blanc has developed an ink that is linked to each individual as matchless as a fingerprint. This new innovation is comprised of components containing an invisible, inimitable botanical code which is similar to the human DNA code. Available from Spring 2010, this revolutionary set of writing instruments with the Personal Code Ink will be offered for the first time in handcrafted Montblanc pens imbued with a new, cutting-edge ink to facilitate the manual art of self-expression.

[From Mont Blanc Offers ‘Personal Code Ink’ For Pure Manual Art Of Self-expression - Born Rich]