Worn by louis cartier himself the tank louis cartier watch sets the standard to be upheld by all tank watches in contrast to the assertive choice of rectangular form and proud lines the tops of the lugs were rounded embodying the contribution made by louis cartier to the modern style later known as art deco18k yellow gold case 18k yellow gold circular grained crown set with a sapphire cabochon mineral crystal silver grained dial roman numerals sword shaped blued steel hands alligator