Perhaps the hottest watch released by Audemars Piguet this year, the Royal Oak Perpetual Calendar makes a new appearance now with an openworked dial and cloaked in a black ceramic case. The new Audemars Piguet ref. 26585CE.OO.1225CE.01 is a true feat of technical mastery with its openworked sapphire dial and the movement’s visible pink gold components. Measuring 41 mm in diameter like all other Royal Oak Perpetual Calendars released as of the end of 2015.