What do serial numbers and date codes on luxury pieces actually tell you?

Start with what a code is for

None of these marks were designed as anti-counterfeiting devices. They are production records: which period a piece was made in, which atelier or factory made it, which model reference it is. They became authentication folklore because they were the only numbers a buyer could see.

That gives them a useful asymmetry, and it only runs one way. A code in the wrong format for the claimed year, in the wrong place, or absent where it should be, is a real reason to walk away. A code that looks right tells you almost nothing — as an authentication service put it about Hermès stamps, they are an excellent initial indicator but not foolproof, because counterfeiters replicate them.

The clearest proof of the limit is a court record. In Chanel's case against What Goes Around Comes Around, the final judgment specifically banned the sale of handbags bearing serial numbers stolen from a factory in 2012 — real numbers, on bags the court treated as counterfeit.

Louis Vuitton

Date codes appeared in the early 1980s and changed format several times: a few digits at first, then digits plus two letters, then from 1990 two letters and four digits encoding month and year, and from 2007 the same shape encoding week and year. The letters are a factory and country code, not a model or authenticity code.

They sit on an interior leather tab sewn into a seam, inside a pocket, or embossed on the lining — the location varies by model, which is itself worth knowing before you decide a bag is missing one.

It is widely reported across the trade that Louis Vuitton stopped applying date codes around March 2021 in favour of an embedded microchip, which consumers cannot read. Louis Vuitton has not published a statement confirming this, so treat it as trade consensus rather than brand fact — but it means a recent bag without a date code is not necessarily wrong.

Chanel

Chanel introduced serial stickers from the mid-1980s: a printed number on an adhesive label inside the bag, paired with a matching authenticity card. The code indicates a production period, not a month or a factory.

One thing worth saying plainly, because almost nobody does: Chanel has never published a complete reference for its serial system. The year-by-year tables you will find online are industry consensus assembled by resellers, not brand documentation.

Trade press reported in 2021 that Chanel had begun replacing the card-and-serial combination with microchips readable only with Chanel's own technology. Chanel's own stated position, from its litigation, is blunter: the only way to be certain of a genuine Chanel product is to buy from Chanel or an authorised retailer.

Hermès

Hermès uses a heat-pressed blind stamp. A letter indicates the year; accompanying characters identify the craftsman or atelier. The shape around the letter used to date it by decade — inside a circle from 1971 to 1996, inside a square from 1997 to 2014 — and from 2015 the shape was dropped and the code format became more complex.

Location moved too: on either side of the strap on older bags, and on post-2016 Birkins and Kellys on the left side of the interior near the back flap.

We are deliberately not publishing a year-letter table. Hermès publishes nothing official, and the tables in circulation contradict each other on recent years. Anyone presenting one as definitive is guessing with confidence.

Rolex

Two numbers matter. The serial number is engraved on the case at the 6 o'clock end between the lugs, and the reference — the model number — at the 12 o'clock end; on older watches you have to remove the bracelet to see either. On modern watches the serial is engraved on the rehaut, the inner flange between the dial and the crystal.

One firmly verifiable fact that undoes a lot of online dating: since August 2010 Rolex serial numbers on new watches have been randomised, so they cannot be used to date a watch at all.

Rolex offers no consumer serial lookup, and its own guidance is to buy from Official Rolex Retailers, who guarantee the authenticity of every part.

Cartier

Cartier pieces typically carry a serial number — on watches near the caseback or between the lugs, alongside a separate case reference; on rings inside the band; on Love bracelets inside, near the clasp. Cartier publishes no serial reference, so the specifics above are trade convention rather than brand documentation.

Cartier's own position on provenance is narrow and clear: the Cartier International Guarantee applies only to pieces bought from a Cartier boutique, e-boutique, phone sale or official retailer. It does not authenticate items bought elsewhere.

What has replaced the code

In April 2021 LVMH, Prada Group and Cartier's parent Richemont founded the Aura Blockchain Consortium to give products a traceable digital identity and give owners access to product history and proof of authenticity. That is the direction of travel: verification moving from a number you can read to a chip the brand can read.

For a second-hand buyer it cuts both ways. Codes become less useful as a check, and the marketplace's own authentication programme — where an organisation physically inspects the item and carries the risk — becomes the thing that actually matters.

Where this comes from

Every figure and rule above is taken from the sources below. Rules, fees and brand practices change — check the source before you rely on it for a specific purchase.

• Xupes — Guide to Louis Vuitton date stamps: history, formats and authentication — published 9 July 2024
• Xupes — Guide to Chanel date codes — published 16 April 2025
• Xupes — Guide to Hermès date stamps — published 9 July 2024
• Lollipuff — Louis Vuitton to replace date codes with microchips
• The Fashion Law — Chanel replacing authenticity cards with microchips (15 October 2021)
• The Fashion Law — Chanel v. What Goes Around Comes Around case study (voided serial numbers)
• Watchfinder & Co. — Watch serial numbers (Rolex serial and reference locations; 2010 randomisation) — 2026-09-19
• Rolex — Watch care and service FAQ — 2026-09-19
• Cartier — International Guarantee FAQ — 2026-09-19
• Richemont — Cartier, LVMH and Prada Group form the Aura Blockchain Consortium (20 April 2021)