The Must de Cartier is a Swiss luxury watch collection first introduced in the 1970s as a creative extension of the Tank line, designed to make Cartier’s signature style more accessible. Recognized for its rectangular case, bold Roman numerals, and sapphire cabochon crown, the collection quickly became an icon in its own right. Vintage Must de Cartier watches are often found in vermeil cases with elegant lacquered dials in striking colors, while modern interpretations of the line, known as the Tank Must, bring updated proportions and options in stainless steel with quartz or Swiss automatic movements. Collectors value the Must de Cartier for its role in expanding Cartier’s influence in luxury watchmaking and for its blend of creativity and refinement. Today, the Must de Cartier remains one of the most collectible Cartier watches for sale, admired for its heritage, charm, and craftsmanship.