Each result explains its dating basis: an exact archive match, an estimate from comparable documented watches, a published serial table, or a date code. When the evidence is insufficient or contradictory, the result asks for more information.

Dates can refer to manufacture, archive registration, delivery or sale. These events are kept separate. A serial number can help date a watch; it cannot establish authenticity.

Archive evidence: this build includes 2,579 archive-backed records across nine brands, including Jaeger-LeCoultre Atmos. The total counts Longines once per movement number, even when it has several dated events. Longines now also uses a clearly labelled secondary archival-database tier for exact matches and conservative fallback interpolation; directly inspected Extract evidence remains the higher tier. For Omega Speedmaster, SpeedyBase’s ★ Extracts registry is used only as a secondary discovery/coverage layer: an entry becomes a strict DateMyWatch archive anchor only when the serial and extract-backed date can be independently tied to an original or public source. I Love My Speedmaster is handled the same way: its prediction output is never treated as an Extract, while publicly disclosed full-serial Extract datapoints from the underlying research can be used with their original source attached; masked or reconstructed serials are excluded. Open “View archive records” in a search result to see the documented watches and their sources.

Estimates use comparable records only where the numbering sequence and available evidence support a meaningful comparison. Reference and caliber can help narrow the result. The displayed range reflects uncertainty; it is not a guarantee or a replacement for the manufacturer’s own archive document.