Patek Philippe holds the original Swiss patent for an annual calendar caliber. The annual calendar complication is a very astute innovation. It provides 99% of the functionality of a perpetual calendar at roughly half the price. The annual calendar keeps track of which months have 30 days versus 31 days; on "short" months the wearer does not need to advance the date. On February 28th the date's next stop is March 1st. The calendar only needs to be reset on February 29th every leap year (making for 1461 days without requiring the wearer's attention).
The Patek Philippe 5146 reference is a recent model from Switzerland's most revered and most respected watch brand. Featuring a newly redeigned, larger case with modern lines, this watch also has a solid gold deployant clasp. The 18k yellow gold case measures 39mm diameter by 11mm thick. Sapphire crystals front and back. Generously sized crown.
The dial is white, which is the most versatile dial color in my opinion. Legibility is improved over Patek's previous generation of annual calendars thanks to the larger case size which has permitted a larger dial to be used. The indicators are as follows: power reserve at 12 o'clock; month at 3 o'clock; moonphase above 6 o'clock with date below it; day at 9 o'clock.
Movement is automatic winding Patek Philippe Caliber 315 IRM QA LU with 355 individual parts, 48 hour power reserve and 36 jewels. Rotor is 21k gold to help with winding efficiency. Stamped with the Geneva Seal.