Hermès has dated its leather since 1945 with a single letter, cycled through the alphabet in four eras: plain letters 1945–1970, a circle 1971–1996, a square 1997–2014, and plain letters again from 2015 in a non-sequential order. A plain letter can therefore mean two different years half a century apart — and the selected model's documented history usually settles which. Enter the letter, pick the shape around it, and the tool answers honestly.
The stamp dates the leather's production year; it authenticates nothing, and superfakes stamp confidently. Pieces before 1945 carry no stamp at all, and absence on true vintage is normal. The letters beside the year letter are craftsman and atelier marks, not part of the date. Known quirks the file records: some Evelynes left the factory with a JO stamp in a rectangle instead of a year letter; some 2011 pieces carry a double stamp; and some late-2014 pieces show the R without its square as the modern system arrived. Recent-year letters are compiled from authentication references and extend as the record does. A stamp whose era disagrees with the model's documented history is itself a finding.