The Rolex Submariner Date Ref. 16613, known as the iconic “Bluesy,” is a magnificent two-tone timepiece that masterfully combines robust Oystersteel with the warmth of 18k yellow gold. This 40mm model is defined by its stunning blue dial and matching blue bezel insert, but what sets this particular watch apart is the rare and captivating phenomenon known as a “tropical” dial . Over decades, the original vibrant blue lacquer has gracefully aged, transforming into a mesmerizing spectrum of purple, lavender, or chocolate hues under the influence of sunlight and humidity . This organic evolution gives the watch a unique, one-of-a-kind character, with the dial shifting from deep blue to rich purple depending on the light, creating a visual spectacle that fascinates collectors and enthusiasts alike . The watch is powered by the legendary in-house automatic Caliber 3135, a COSC-certified chronometer renowned for its robustness and precision, offering a reliable 48-hour power reserve. The iconic two-tone Oyster bracelet, featuring solid gold center links, provides both durability and a luxurious aesthetic, secured by a folding Oysterlock clasp . With a 300-meter water resistance and a scratch-resistant sapphire crystal, this 1987–1990s reference 16613 is a vintage treasure that perfectly blends the rugged functionality of a professional diver’s watch with the unmistakable prestige of a precious metal Rolex, making it a highly sought-after piece for the discerning collector who values history, patina, and enduring style .