PATEK PHILIPPE | NAUTILUS, REFERENCE 3712 A BRAND NEW STAINLESS STEEL BRACELET WATCH WITH DATE, POWER RESERVE INDICATION AND MOON PHASES IN DOUBLE FACTORY SEAL, CIRCA 2006" | 百達翡麗 | Nautilus 型號3712 全新精鋼鏈帶腕錶，備日期、動力儲備及月相顯示，原廠未開封，機芯編號3171437，錶殼編號4329698，約2006年製"

The Nautilus reference 3712 was introduced in 2005 and had a very short production run. It is believed to have been made for only eight months and therefore the overall production output is rather low with an estimate of 1700 pieces being sold. At the time of production it was the most complicated Nautilus as it included, in addition to the date which previous models already had: moon phases, a power-reserve indication and subsidiary seconds. The way those indications and apertures are placed on the dial is particular, giving the watch a special touch. 

It was replaced in 2006 by the similar reference 5712, which was introduced to commemorate the 30th anniversary of the iconic Nautilus model. The two models can be distinguished by a subtle difference to the dial, specifically the very small applied index at 7 o'clock which could be found on the 3712 but not on the 5712.