Half the mistakes in the secondhand bag market are dating mistakes wearing other costumes. The "fake" Chanel with era details that are perfectly correct for a year the seller never considered. The Louis Vuitton priced as 2008 that the code plainly says is 2018. The Balenciaga listed as an original that its own tag dates to last spring. Authentication arguments, condition arguments, price arguments, and underneath most of them, nobody ever established when the bag was made, which is the one question the bag itself usually answers in under five minutes. So here is the entire system, all seven maisons in my files, in the order I'd check them. The instruments below do the decoding; this article is the manual.
Chanel: the serial, 1986 to 2021
From 1986 until early 2021, every Chanel bag carried a unique serial number, on a sticker inside the bag and repeated on its authenticity card, and the number's leading digits date it: seven digits from 1986 to 2005, eight digits after, with the first one or two digits naming the series and each series mapping to a year band. The Chanel serial lookup holds the whole table. Then, in April 2021, the system ended: stickers and cards gave way to a microchipped metal plate whose code is random and dates nothing. Which means Chanel dating is now a closed historical record with a beginning and an end, and it also hands you two free verdicts: a post-2021 bag with both a chip and an authenticity card is wrong, because the card died with the sticker, and a pristine sticker in a heavily worn vintage bag deserves suspicion, because stickers age with the bags they live in. The trap to respect: stickers are the most replaced, most faked component in the whole Chanel exam, so the serial dates the bag only when the era details, hardware, stitch counts, lining, agree with the date it gives.
Louis Vuitton: the code, and the 2007 trap
Louis Vuitton's date codes ran from the early 1980s to 2021, settling into their long two-letters-and-four-digits format: letters for the factory's country, digits for the date. The decoder handles every era, but one switch inside the system causes more misdatings than everything else combined, and it deserves its warning in bold: in 2007 the digits changed meaning, from month and year to week and year. Before 2007, the first and third digits are the month; from 2007, they are the week of the year. Read a late code with the early rule and a week-46 bag becomes a month that does not exist, or worse, quietly lands in the wrong year; read an early code with the late rule and you invent a date the factory never stamped. The decoder applies the right rule automatically, which is exactly why I built it. And like Chanel, the system has an end: 2021, when the maison moved to embedded chips and stopped stamping codes entirely. A current-production bag with no code is correct. The other doctrine worth engraving: an LV code is a birth certificate, not a fingerprint, thousands of bags share each code, so it dates and it does not authenticate.
Hermès: one letter, four eras
The oldest system in the files is also the smallest: since 1945, Hermès has dated its leather with a single stamped letter, the blind stamp, cycling through the alphabet in eras marked by the shape around the letter, plain letters first, circled from the early 1970s, squared from 1997, then plain again after 2014 in a scrambled order. One letter, cycling, means one letter can mean several years, and the blind stamp tool resolves it the way Case 01 explained: against the model's own documented history. A plain A on a Birkin can only be the modern era, because in 1945 the Birkin was still four decades from existing. The tool's bluntest verdict, STAMP AND MODEL DISAGREE, remains the shortest authentication lesson this site has ever published.
Dior: the code that dates and places
Every Dior since roughly 1997 carries a small stamped code, usually on the interior leather tab, that encodes the factory and the production date, and the Dior decoder reads both. Its highest-stakes job on this site is generational: the Saddle's original run and its 2018 revival sit on opposite sides of the code eras, so the code settles the original-or-revival question, and the money question with it, before the photographs get a vote. That pattern, the code as generation referee, is the whole thesis of the Comeback File, and Dior is where it works most cleanly.
Balenciaga: the alphabet that runs backwards
The newest instrument in the toolbox decodes the strangest system: from Fall/Winter 2003, Balenciaga tags carry a season letter that runs backwards through the alphabet, two seasons a year, and because the alphabet has now cycled, most letters mean two possible seasons, a D is Fall 2003 or Spring 2016, split by tag features the season letter decoder asks you about: the 925 silver stamp points early, the letter repeated on the tag's back or the large MADE IN ITALY print points late. Two rules from its file are worth repeating anywhere. First, production before Fall 2003, the earliest Firsts and Cities, carries no letter at all, so a letterless tag on claimed early production is correct, not suspicious, and a letter on a claimed 2001 bag is the problem. Second, the letters E through J and X were only ever used once, so they date without any ambiguity at all, the alphabet's honest citizens.
The two refusals: Gucci and Prada
Now the part that saves people money: two of my seven maisons do not date their bags, and every guide that claims otherwise is selling a decoder for a code that does not exist. Gucci's serial tags encode the style and the supplier, not the date, so a listing that dates a Jackie off its tag has told you what kind of listing it is; Gucci bags are dated by era details and provenance, as their files explain. Prada encodes no dates anywhere, and the white factory tag inside is a factory number, not a year. The absence is the doctrine: when a house declines to date its bags, the correct answer to "what year is it" is a range built from design details, and any seller offering false precision has just been generous with a warning.
The traps, collected
Every system above has one failure mode that does most of its damage, so here they are in one place. Chanel: the replaced sticker, date only what the era details confirm. Louis Vuitton: the 2007 month-to-week switch, the single most productive misdating machine in the market. Hermès: the cycled letter read without the model's history. Dior: revival bags sold on original-era romance, when the code settles it in seconds. Balenciaga: the cycled alphabet, and the letterless early tag mistaken for a flaw. And across all seven: the microchip era means the newest bags date by paperwork and provenance, not codes, so "no code" is now a correct answer for three houses, for opposite reasons.
Why the order matters
Date first, authenticate second, price third. The date is the frame every other judgment hangs in: era details can only be right or wrong relative to a year, so authentication without a date is opinion with good lighting. And the price follows the generation, not the silhouette, as every revival pair in the Comeback File proves: a 2005 City and a 2024 Le City, a 1999 Saddle and a 2018 one, are different objects at different money wearing the same shape. Five minutes with the right instrument sorts all of it before a dollar moves. The instruments are free, they live on this site, and they do not care what the listing says. The listing expires; the file doesn't.