Cartier Tank ‘Onyx’Heres another beautiful Must de Cartier Tank watch, this time with a stunning, glossy black lacquered dial, also known as the Onyx Tank among the vintage Must de Tank watches it is a timepiece that is a downright icon and this particular example shows a dial without any cracks, spider dial effect or damages. and is a watch accompanied by the original box and papers. The black dial on our Cartier Tank is a dial without any hour, minute or seconds