A used Rolex Datejust 31 is the 31 mm version of Rolex's classic date watch, sold in steel, two-tone, and solid gold across references such as 178240, 178273, 278240, and 278273. Buying pre-owned gives you access to discontinued dials and bezel combinations and usually costs less than a new example, but condition and completeness decide the real value.
Where the Datejust 31 sits in the lineup
The Datejust 31 sits between the 28 mm Lady-Datejust and the 36 mm Datejust. Rolex presents it as a mid-size watch, and on most wrists it wears closer to a dress piece than a sport model: slim lugs, a low profile, and a bracelet that tapers toward the clasp. That middle position is why the used market for this size is broad, with buyers ranging from people who want a smaller daily watch to those shopping for a partner.
Reference numbers worth knowing
Rolex reference codes are not random. The first digits identify the case generation, and the trailing digits signal bezel and bracelet type, which is why two watches that look similar on a listing can be very different pieces.
- 6824 and 6827: early 31 mm cases from the 1970s, now collectible and often found with service parts.
- 178240 family: 2000s generation, steel case, mostly with the caliber 2235 and a sapphire crystal.
- 178273, 178274, 178278: same era, with two-tone, white gold fluted, or full yellow gold configurations.
- 278240, 278273, 278274, 278278: current generation introduced from 2016, using the caliber 2236 with a longer power reserve.
When you compare listings, note the full reference rather than the model name alone. A fluted white gold bezel or a President bracelet changes the price far more than the dial color does.
How the 31 mm size wears
Case diameter is only part of the story. The Datejust 31 has a short lug-to-lug span, so it fits smaller wrists without overhang, and it slides under a cuff more easily than a 36 mm model. If you are deciding between sizes, try a 31 and a 36 side by side on your own wrist. Photos on a listing rarely show how the bracelet sits on the top of the wrist, which is the part that decides comfort.
What to inspect on a used example
Condition grading is where most of the money sits in this reference. Go through the watch in person or ask for close, well-lit photos of each point below.
- Case and lugs: look for heavy polishing that rounds the lugs or softens the caseback edge.
- Bracelet stretch: hold the watch sideways and check the gap between links, especially on Jubilee bracelets.
- Crystal and bezel: chips on a fluted bezel are hard to repair and cost real money.
- Dial originality: refinished dials and aftermarket diamonds reduce value and complicate resale.
- Movement service history: ask for the date of the last service and any paperwork that proves it.
- Box, papers, and warranty card: full sets hold value better and make authentication simpler.
What drives the price
Four factors explain most of the spread in asking prices: case metal, bezel type, bracelet type, and completeness. Steel models with a smooth bezel and Oyster bracelet sit at the accessible end. Two-tone and full gold versions cost more because of the metal content. Dials that were produced for a short run, such as certain stone or lacquer finishes, carry a premium that has nothing to do with the movement. Age matters less than condition, so a well-kept 2005 example can be a better buy than a worn later model.
Authenticity and the copy market
The Datejust 31 is one of the most copied watches in the world, which means the used market includes replicas dressed up as genuine pieces. Before paying, verify the serial and model number between the lugs against the paperwork, check the crown engraving on the clasp, and have a watchmaker open the case to confirm the movement. A price that sits far below the rest of the market is the clearest warning sign.
Quick buying checklist
- Confirm the full reference number, not just the model name.
- Match the case size to your wrist before you commit.
- Request dated service records or budget for a service.
- Check bracelet stretch and bezel condition in photos.
- Verify the serial and have the movement inspected.