{"product_id":"rolex-datejust-31-black-roman-178240-circa-2004","title":"Rolex - Datejust 31 – Black Roman – 178240 – Circa 2004","description":"\u003cp\u003eThe Rolex Datejust 31 brings the proportions of the classic Datejust to a refined 31mm case, a size that sits elegantly on the wrist while keeping every element that has made the Datejust an icon since 1945: the Oyster case, the date window at 3 o'clock and the magnifying Cyclops lens. The reference 178240 is the stainless steel version with a smooth domed bezel, giving it a clean, understated profile. This configuration pairs a black dial with Roman numeral hour markers for a crisp, timeless look.\u003c\/p\u003e\n\u003cp\u003eInside is the Rolex calibre 2235, a self-winding mechanical movement manufactured in-house and designed specifically for Rolex's mid-size and ladies' Oyster models. It drives the hours, minutes, central seconds and an instantaneous date, with a power reserve of approximately 48 hours. The screw-down winding crown and Oyster case provide water resistance to 100 meters, and the watch is completed by the three-piece link Oyster bracelet.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSpecifications\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBrand: Rolex\u003c\/li\u003e\n\u003cli\u003eCollection: Oyster Perpetual Datejust\u003c\/li\u003e\n\u003cli\u003eModel: Datejust 31\u003c\/li\u003e\n\u003cli\u003eReference: 178240\u003c\/li\u003e\n\u003cli\u003eCase: Stainless steel (904L)\u003c\/li\u003e\n\u003cli\u003eCase Diameter: 31mm\u003c\/li\u003e\n\u003cli\u003eDial: Black\u003c\/li\u003e\n\u003cli\u003eHour Markers: Roman numerals\u003c\/li\u003e\n\u003cli\u003eMovement: Rolex calibre 2235, self-winding mechanical\u003c\/li\u003e\n\u003cli\u003ePower Reserve: Approximately 48 hours\u003c\/li\u003e\n\u003cli\u003eFrequency: 28,800 vph (4 Hz)\u003c\/li\u003e\n\u003cli\u003eJewels: 31\u003c\/li\u003e\n\u003cli\u003eCrystal: Sapphire with Cyclops lens over the date\u003c\/li\u003e\n\u003cli\u003eWater Resistance: 100 meters\u003c\/li\u003e\n\u003cli\u003eStrap\/Bracelet: Oyster bracelet, stainless steel\u003c\/li\u003e\n\u003cli\u003eFunctions: Hours, minutes, central seconds, instantaneous date\u003c\/li\u003e\n\u003cli\u003eSpecial Features: Superlative Chronometer (COSC certified)\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Investment Watches Inc","offers":[{"title":"Default Title","offer_id":57597880631622,"sku":"A2461","price":5750.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0630\/5559\/3658\/files\/white-Photoroom-2026-11-13T104734.677.webp?v=1794588462","url":"https:\/\/www.investmentwatches.com\/products\/rolex-datejust-31-black-roman-178240-circa-2004","provider":"Investment Watches Inc","version":"1.0","type":"link"}