Ultra-thin watches are an important trend in high watchmaking at the moment, and Cartier’s extraordinary new model in this category, introduced at the SIHH in Geneva, is the elegant Ballon Bleu Extra Flat. This watch is only 6.9mm thick, with an elegant, 40mm width, making it the ideal watch to wear with a dress shirt, as it will slip easily under the cuff. The outstanding dial is grey flinqué, a wavy guilloché treatment that involves hand engraving, and demonstrates just how great grey looks with rose gold. The blue sapphire crown, protected by a curved arch, is a signature of the Cartier Ballon Bleu line. Other Cartier signature elements include the Roman numerals, railtrack minute circle and sword shaped hands. It contains a Cartier manufacture manual wound movement. For anyone looking for a little more flash, there is a diamond set version.