The current title holder for the world’s most expensive pen is the Fulgor Nocturnus by the famous pen-makers Tibaldi of Florence. This fountain pen sold for $8 million in a 2010 auction in Shanghai, China.
So what’s so special about the Fulgor Nocturnus that makes it about 8 million times more expensive than your average Bic pen? It was created based on the Divine Proportions of Phi, so the ratio between the cap and the visible portion of the barrel when the pen is closed is equal to the phi ration 1.618. In addition to its divine shape, the pen is decorated with 945 black diamonds and 123 rubies.