The new Piaget Polo Perpetual Calendar Green Obsidian in a limited edition of only 18 pieces—individually numbered—is equipped with a 42 mm case in 18K white gold housing a striking dark emerald-green obsidian dial with a date indicator at 3 o'clock, a month and leap-year indicator at 12, the day of the week at 9 and the small moon phase display at 6 o'clock.