The one-of-a-kind Rouge & Noir Ultimate Serpent Limited Edition 1 weighs in at 130g, with 99g of rose gold—the highest amount of gold ever used in the manufacturing of a Montblanc fountain pen.

The pen was a Diplomat, the biggest Mont Blanc makes. Whoever found it, he says, "got quite a prize." In the 1980s, that model cost a couple of hundred dollars. The 2008 version retails at $635.