Datejust 31 Stainless Steel Domed / Oyster / Black Roman

About This Watch

The Rolex Datejust 31, in its 178240-0034 iteration, embodies the quiet authority of a timepiece that has defined elegance for generations. With a 31-millimeter stainless steel case, its domed profile and Oyster construction evoke the enduring silhouette of the Datejust collection, first introduced in 1945 as a symbol of refined precision. The black dial, adorned with crisp Roman numerals and slender stick hands, offers a timeless contrast to the polished stainless steel, balancing sophistication with approachable luxury. The sapphire crystal, paired with a closed case back, ensures durability without compromising the watch’s discreet, understated presence. At its heart lies the Caliber 2235, an automatic movement distinguished by its enhanced date mechanism and a 70-hour power reserve, reflecting Rolex’s relentless pursuit of mechanical excellence. This reference, while faithful to the Datejust’s heritage, subtly modernizes its proportions for a contemporary wearer, retaining the collection’s hallmark balance of heritage and innovation. The 16-millimeter lug width and 100-meter water resistance further underscore its versatility, making it equally at home in formal settings or casual environments. This watch speaks to those who value legacy without ostentation—individuals who seek a companion piece as enduring as their own discernment. It is not a statement, but a silent testament to the quiet confidence of someone who understands that true luxury lies in precision, craftsmanship, and the unspoken language of time.

In Context

At 31 mm it is small by current standards, in the range most wristwatches occupied before cases began growing through the 1990s. The case back is closed, so the movement stays out of sight, and the sapphire crystal will resist everything short of deliberate abuse. 100 m is genuine swimming resistance — more than the shape of this watch suggests it would need.

The movement winds itself from the motion of your wrist. 48 hours of reserve is enough to set it down on Friday evening and find it still running on Monday. At 28,800 vph the seconds hand advances 8 times a second.

178240-0034 is one of 24 executions of the 178240 base reference. Underneath they are the same watch; what separates this one is a black dial and a stainless steel case.

Rolex

Grey · Stainless Steel

178240-0001 · 31 mm

Rolex

Silver · Stainless Steel

178240-0005 · 31 mm

Rolex

Grey · Stainless Steel

178240-0006 · 31 mm

Rolex

Black · Stainless Steel

178240-0011 · 31 mm

Rolex

White · Stainless Steel

178240-0015 · 31 mm

Rolex

Black · Stainless Steel

178240-0016 · 31 mm

Rolex

Pink · Stainless Steel

178240-0017 · 31 mm

Rolex

Black · Stainless Steel

178240-0019 · 31 mm

+ 15 more variants in this family.

The 2235 is the small Rolex automatic of the six-digit generation, a 20 mm movement with a date. It carried the Datejust 31 and the 26 mm Lady-Datejust from around 2000 until the 2236 replaced it. It powers 733 watches in this library. It has 31 jewels, a 48-hour reserve and a beat of 28,800 vph, and every one is a COSC chronometer. It is the same architecture as the [2236](/calibers/rolex-2236) that followed, without the silicon Syloxi hairspring and with seven hours less reserve; the [2236 piece](/blog/the-rolex-2236-the-most-common-movement-in-this-library) explains what changed. The library finds it almost entirely in the [Datejust 31](/brands/rolex/datejust-31): 682 references, the 1782xx generation, whose 45 base references and hundreds of dial variants make that collection the largest here. The 26 mm [Lady-Datejust](/brands/rolex/lady-datejust) of the 1791xx generation accounts for 29, the [Pearlmaster](/brands/rolex/pearlmaster) 29 mm and 34 mm for 19, and the 35 mm Yacht-Master for 3. A six-digit Datejust 31 reference is a 2235; the seven-digit one is a 2236, as the [reference-number guide](/blog/how-to-read-a-watch-reference-number) explains. The 2231 was its no-date sibling in the Oyster Perpetual, and the [3135](/calibers/rolex-3135) its counterpart in the 36 mm cases.

732 other watches in the library run the Rolex 2235.

Rolex

Datejust 31 Yellow Gold Diamond / Oyster / Black MOP

178158-0056 · 31 mm

Rolex

Datejust 31 Stainless Steel Diamond / Oyster / Pink MOP

178384-0061 · 31 mm

Rolex

Datejust 31 Rolesor Everose Domed / Jubilee / Black MOP

178241-0043 · 31 mm

Rolex

Datejust 31 Yellow Gold Domed / Oyster / Champagne Roman

178248-0079 · 31 mm