The Ref. 5970 - a writs-chronograph with perpetual calendar - represents a “Must” in the production of the Genevan manufacture. This model is the heir to an impressive series of watches that has ensured the reputation of the brand among collectors. It all started in the 1940’s with the launch of Ref. 1518, which will be followed in the 1950’s by Ref. 2499, then in the 1980’s by the Ref. 3970. If these models are now highly coveted by amateurs, it is due to the fact that after the Second World War, Patek Philippe was the only watchmaker in the world to be able to produce in series this kind of parts, certainly in a few examples each year but of a remarkable quality of execution. The Ref. 5970 was launched in 2004 and will be produced until 2011. It remains today a very popular model among collectors, not only because its classic line is timeless but also because it incorporates the latest movements of manual-winding chronograph made by the manufacture (based on a highly improved Lémania calibre) - the Cal. CH 27-70 Q -, before Patek Philippe presents his own movement used for the new Ref. 5270. The Ref. 5971 was launched in 2007, with a platinum case, a bezel set with 36 baguette diamonds (total WEIGHT around 4 carats, Top Wesselton quality) and a black lacquered dial. It remains available in the product catalogue for just three years. It can therefore be reasonably assumed that the number of examples sold should not exceed one hundred units. The Ref. 5971 remains in the eyes of connoisseurs the “Classic column-wheel chronograph with perpetual calendar, accented by the eternal fire of diamonds”