In 1977, Cartier opened its doors a little wider with Les Must de Cartier, offering its celebrated Tank in vermeil, sterling silver dressed in gold. The line soon became a playground of colour, from deep burgundy and glossy black to tortoiseshell and the three-gold Trinity dial. Among them, this midnight blue lacquer scattered with gold flecks, an echo of lapis lazuli, is one of the loveliest, and one you come across far less often.