Section 18 OPTICAL, PHOTOGRAPHIC, CINEMATOGRAPHIC, MEASURING, CHECKING, PRECISION , MEDICAL OR SURGICAL INSTRUMENTS AND APPARATUS; CLOCKS AND WATCHES; M USICAL INSTRUMENTS; PARTS AND ACCESSORIES THEREOF 91 Clocks and watches and parts thereof 91 13 Watch straps, watch bands and watch bracelets, and parts thereof. 91 13 90 Commodity Code Description 91 13 90 00 91 13 90 10 Of natural or cultured pearls, precious or semi-precious stones 91 13 90 90 Other