Perpetual calendars come in all forms, shapes, metals and prices. However, few brands stand out from the rest as far as their perpetual calendars in terms of history, reliability and prestige. When you are looking for a perpetual calendar the first brand names that pop up would be Patek Philippe, Audemars Piguet and Vacheron Constantin as these make the ‘holy trinity of watchmaking’. The Audemars Piguet Royal Oak Perpetual —Quantième Perpétuel— ref. 26574 was released at the end of 2015 and since then, it holds ‘watch grail status’.