Patek Philippe reference 1591 from Most Expensive Watch

This common looking stainless-steel watch, which was auctioned at the price of 2,200,000 in 2007, and became the most expensive stainless – steel watch ever sold. This rarity contains stainless steel water-resistant perpetual calendar with indirect sweep centre seconds, phases of the moon and luminous indexes. It is believed that this watch is the only stainless steel example of reference 1591 ever made, and one of only two existing examples of this model ; the second of which is cased in yellow gold.