The Rolex Sea-Dweller reference 126603 is the watch that ended nearly fifty years of all-steel tradition when Rolex introduced the first and only two-tone Sea-Dweller at Baselworld 2019. Combining Oystersteel with 18k yellow gold on the bezel, winding crown, and bracelet center links — what Rolex terms Yellow Rolesor — the 126603 brings precious-metal elegance to a model line engineered originally for professional saturation divers operating at the outer limits of human depth. The 43mm Oyster case is rated to 1,220 meters of water resistance and equipped with the helium escape valve that permits safe decompression after extended saturation, paired with the unidirectional 60-minute Cerachrom ceramic bezel finished with yellow gold numerals. The black lacquered dial carries large Chromalight applied indices and Mercedes hands, with the date at three magnified by the Cyclops lens — a cosmetic feature that arrived on the Sea-Dweller for the first time with this reference. Powered by the in-house Rolex Caliber 3235, a Superlative Chronometer with paramagnetic blue Parachrom hairspring, Chronergy escapement, Paraflex shock absorbers, and approximately 70 hours of power reserve. Worn on the matching Oyster bracelet with Glidelock and Fliplock extension systems. 2020 production, pre-owned in excellent condition. Affirm financing available at checkout.