The IWC Portugieser Perpetual Calendar 5023 was introduced in 2010, pairing IWC's self-winding 7-day movement with Kurt Klaus' ingenious perpetual calendar module. The latter was first seen in the 1985 Da Vinci and adapted to fit the larger dimensions of the 7-day movement. It featured a case of 44.2mm with sapphire glasses both front and back. One of its signature elements was the 'Single Moon' moonphase display, allowing its owner to read the moonphase in its hemisphere. This reference, the IW5023-07, features a white gold case with an ardoise colored dial. It was introduced in 2011.
