Launched in 2010 in yellow gold, Patek Philippe's Ref. 5170 is the chronograph to which all others aspire. The purist proportions and nods to classic Patek chronographs of old - subdials that intersect the chronograph seconds register; a pulsometer scale around the edge - have already gone down in watchmaking history. The latest 5170G in white gold replaces the hour markers with Arabic-style numerals, but the hand-wound chronograph, the CH 29-535 PS - developed in-house by Patek Philippe - remains the same. Fitted with a number of Patek-patented innovations, this technically brilliant chronograph is as beautiful on the inside as it is on the outside.