Cartier's new Tank Must watches. Photo courtesy Cartier. Last week, Cartier debuted three new watches that pay homage to one of the luxury French house’s earliest design risks: the decision by founder Louis Cartier to produce a watch shaped like a rectangle in 1917 in lieu of the day’s more conventional circular style. Though the idea may sound simple, at the time it was perceived as a particularly avant-garde move to center design over utility, which was met with a good deal of skepticism in the highly conservative world of haute horology. But Cartier’s design innovation didn’t sa...