Identify a Longines From a Photo: Reference and Serial Guide

On a modern Longines, both numbers are on the caseback. The reference follows the format L#.###.#.##.#, for example L3.774.4.50.6, and sits alongside a serial number, the water resistance and the material. On a display caseback they are engraved around the metal rim. Both numbers are also printed on the warranty card, so a watch sold with its card can be checked in seconds.

Vintage Longines watches work differently. There is no catalogue-style reference on the outside of the case. The serial number is engraved on the movement, usually on a bridge next to the calibre designation such as 12.68Z, 30L or 13ZN, and this is the number the Longines archives are indexed by. The case carries a separate case number inside the caseback, often with the winged hourglass and metal hallmarks. The two numbers are not meant to match, and a seller who quotes only the case number has not given you what you need.

Reading the movement serial means opening the caseback, so when buying at a distance ask for a photograph of the movement. If the dial is signed Longines but the movement is not, treat the watch as unverified. For how other brands place these numbers, see our guide to watch reference numbers.

Modern Longines references have five groups separated by full stops. Longines does not publish a decoding table, so what follows is the pattern collectors have observed: it holds well, but treat the detail as a guide rather than a rule.

• L and one digit: the collection group. Broadly, L2 is the classic and heritage lines (Master Collection, most Heritage pieces), L3 the sports lines (HydroConquest, Conquest, Spirit, Legend Diver), L4 the slim classics (La Grande Classique, Elegant) and L5 the DolceVita.
• Three digits: the model: case, size and movement layout. Adjacent numbers often denote sizes of the same watch; the Spirit is 810 at 40 mm and 811 at 42 mm.
• One digit: the case material. 4 is stainless steel and covers most of the range; 5 is steel with gold cap; other digits cover gold, PVD-coated and diamond-set cases.
• Two digits: the dial. Within a collection the same code recurs: 78 is the silver barleycorn dial across the Master Collection, 11 the white dial of the slim classics. The same digits mean something else in another collection.
• One digit: the bracelet or strap. 6 is a steel bracelet, 7 a two-tone bracelet, and 2, 3 and 0 are leather, alligator and rubber or textile straps.

The dial and strap digits change far more often than the first three groups, which is why one Legend Diver appears under several references and why a photo alone rarely settles the last three digits.

Longines has kept production ledgers since its factory opened in 1867, and its heritage department still consults them. That makes the brand unusual: the serial on a vintage Longines movement can be traced to a calibre, a delivery date and a destination. The collector tables that circulate online are compiled from real extracts and are reasonably good at the decade level, but they are approximate and Longines has never published an official version.

As decade-level anchors only:

• Serials below about one million belong to the nineteenth century.
• Serials from roughly one to five million cover the 1900s to about 1930.
• Serials from roughly five to ten million cover the 1930s to the mid-1950s; the 13ZN chronographs sit in this range.
• Serials from roughly ten to twenty million cover the mid-1950s through the 1970s, including the Conquest, Flagship, Admiral and Ultra-Chron families.
• Above that the serial is of little use; for a modern L-reference watch the warranty card, not the serial, dates it.

The authority is the Extract from the Archives. Given the movement serial and photographs, Longines issues a document stating the calibre, the date the watch was invoiced and left Saint-Imier, and the agent or country it was delivered to, sometimes with the case metal. Longines has historically provided extracts free of charge through an online form; check the brand's heritage services page for the current procedure. A separate certificate of authenticity, which requires sending the watch to Switzerland, has also been offered.

Be clear about what the extract confirms. It tells you that a movement with that serial was made and delivered as described, not that the case and dial in front of you left the factory with it: movements are moved between cases and dials are refinished. The test is consistency between the movement serial, the case number and hallmarks and the dial style, all of which should fit the same period. Our vintage watch collecting guide covers that method for any brand.

• The winged hourglass: the emblem sits above the LONGINES wordmark on the dial, on the crown and on the caseback. Registered in 1889, it is one of the oldest trademarks still in use unchanged. Modern dials add Automatic or Quartz beneath the name; chronometer-certified lines add five stars.
• Master Collection: introduced in 2005, with a pressed barleycorn dial, blued steel hands and Roman or painted Arabic numerals. Date, moon phase, retrograde and chronograph versions share the look, in 38.5, 40 and 42 mm.
• HydroConquest: a 300 m diver with a unidirectional bezel, ceramic insert since the 2018 update, crown guards, a screw-down crown, large Arabic numerals at 12, 9 and 6 and a date at 3. Sizes run from 39 to 43 mm.
• Conquest: the fixed-bezel sports line, with a screw-down crown and the Conquest name on the dial; the Conquest V.H.P. is the high-precision quartz version and says so on the dial.
• Spirit: launched in 2020 as a pilot's watch, with applied Arabic numerals, a large grooved crown, Chronometer on the dial and five stars beneath the name. The Spirit Zulu Time adds a GMT hand and a bidirectional 24-hour bezel.
• La Grande Classique de Longines: a very thin quartz dress watch from 1992, in 24 to 38 mm, usually with Roman numerals or diamond indices.
• Legend Diver: a compressor-style diver reissued in 2007 from a 1960 original, with an inner rotating bezel driven by a second crown at 2 o'clock and the winding crown at 4. First in 42 mm, later also in 36 and 39 mm, with and without a date.
• Heritage reissues: the Heritage Classic sector dial, the speckled-dial Heritage Military, the Heritage 1945, the Skin Diver, the Avigation BigEye chronograph and the 2022 Ultra-Chron reproduce vintage dials in modern cases. The caseback, with its L-reference and often a sapphire window, is the quickest way to tell a reissue from an original.
• Vintage pieces: the 13ZN (from 1936) and 30CH (from 1947) are column-wheel flyback chronographs and the most sought-after Longines of all; only the movement confirms the calibre. Among three-handers, a 1950s Conquest carries an enamel fish medallion on the caseback, a Flagship a ship medallion, and the 1967 Ultra-Chron, a 36,000 vph high-beat watch, is named on its dial.

• Longines, Tissot or Hamilton: all three belong to the Swatch Group and use ETA-built movements, so cases and layouts can look related. The reference formats differ: Longines references begin with L, Tissot's with T (T120.407.11.041.00) and Hamilton's with H (H70455533), and Longines calibres carry L names such as L888 and L688. Omega sits above Longines in the same group; see our Omega identification page.
• Legend Diver or another compressor diver: the two-crown layout with an inner bezel was used by many brands in the 1960s and is copied by microbrands today. Look for the winged hourglass on the dial and crown and an L3.674 or L3.774 reference on the caseback.
• Reissue or original: Heritage models reproduce 1940s and 1950s dials faithfully. Size gives it away first, as originals are mostly 33 to 36 mm, and the caseback settles it.
• Redials: refinished dials are common on vintage Longines and sharply reduce value. Check the print sharpness, the proportions of the winged hourglass, the alignment of SWISS at the foot of the dial and the numeral fonts against period catalogue photographs. An Extract from the Archives says nothing about the dial.
• Longines-Wittnauer: Wittnauer was the brand's United States agent, and from the 1950s the two traded as the Longines-Wittnauer Watch Co. American-market Longines were often cased locally in gold-filled or gold cases by US casemakers, so a Longines movement in a case stamped by an American maker is normal, not a sign of a marriage. A watch signed Wittnauer alone is a Wittnauer, not a Longines.
• Counterfeits: the HydroConquest, Master Collection and La Grande Classique are all copied. Caseback engraving, barleycorn pressing and movement finishing are the places to look; our guide to spotting a fake luxury watch covers the general method.

Upload a photo at watchid.app/identify and WatchID compares the case, bezel, dial layout, hands and logo against known Longines models and returns ranked reference candidates. For a modern watch, match the L-reference on the caseback to the list; a 40 mm and a 42 mm Spirit look the same in a photo but carry different model digits. For a vintage watch, expect a collection and an era rather than an exact reference, since the case does not carry one, and go further with the movement serial and an Extract from the Archives.

1. Photograph the dial straight on, with the text beneath the winged hourglass legible.
2. Photograph the caseback, or the movement if the watch is vintage and already open.
3. Check the candidate reference against the engraving before relying on it.

To see what a reference sells for, and to compare dial and strap variants side by side, browse the Longines listings on Horoview. If the watch turns out not to be a Longines, our Seiko page covers another brand whose caseback is unusually informative. For the general method, read how to identify a watch from a photo.