This Patek Philippe 5085/1J-001 is the Neptune at its most elusive, a solid gold reading of a sports line Patek built overwhelmingly in steel before discontinuing it, which leaves the gold examples as a knowing pick for collectors who follow the references most people overlooked. It runs the automatic caliber 240/164, built on the ultra-thin micro-rotor 240 and among the slimmest self-winding movements Patek has produced, here driving a pointer date, moon phase and power reserve indication. The case is 18k yellow gold, 37mm in diameter and 9.5mm thick, compact and easy on the wrist with the integrated silhouette of a late-nineties sports watch. The dial is silver. Introduced in 1998 and retired by 2006, the Neptune stands as one of Patek's least understood modern chapters, and in yellow gold it is the version that surfaces least.