How to Date a Wristwatch

How old is my watch? A wristwatch is dated in three steps: the outside, the dial and the inside. The size of the case and the lugs give a first time frame, the luminous material and the texts on the dial narrow it down, and the serial and reference numbers in the case or on the movement give, for the big makes, a year of manufacture that can be looked up in tables.

Facts

Start with the case

The first wristwatches were often pocket-watch movements in small cases with wire lugs, where the strap was threaded through a wire soldered to the case. The Cartier Santos of 1904 and the Tank of 1917 showed how a watch could be designed for the wrist from the start, and after the First World War the wristwatch became the man’s watch. In the interwar years cases were small, often rectangular, tonneau-shaped or stepped in Art Deco.

Lugs, the strap attachments, replaced wire lugs in the 1920s and 30s. Round cases of 30–35 millimetres were usual in the mid-20th century, and size has grown since the 1990s. A domed plastic crystal is typical of watches from the middle of the 20th century, whereas sapphire crystal became common later. The diagram of watch cases further down shows the names of the parts: case, bezel, lug, crown and crystal.

The dial and the luminous material

Luminous numerals and hands were long made with radium, which was used until the 1960s and which harmed the women who painted the dials. Radium paint turns dark, brownish or almost black with age and no longer glows. It was replaced by tritium, often marked with a T on the dial, and tritium has in turn been replaced by photoluminescent paints with no radioactivity. Never handle an old radium dial that is breaking up.

The texts on the dial also help. The brand name, the model name and the origin have been written in different ways over the years, and for well-known models there are detailed surveys of every variant. Functions date a watch: a rotating bezel and large luminous indices show a diver’s watch from the 1950s onwards, and a tachymeter scale a chronograph such as the Omega Speedmaster. Be aware that dials have been replaced or repainted, which is common on older watches.

Mechanical, automatic or quartz

The movement is the most important marker of date. Hand-wound mechanical watches dominated for a long time; automatic winding with a swinging rotor broke through after the Rolex Oyster Perpetual of 1931, and the Bubbleback got its name from the domed back that housed the rotor. Date windows became common after the Second World War, with the Datejust of 1945 as an early example.

A quartz watch cannot be older than 1969, when the Seiko Astron appeared. Quartz watches often have a battery cover in the case back and a seconds hand that jumps one step a second. Digital watches with LEDs appeared in the 1970s and were followed by liquid crystals, and plastic cases became common with watches such as the Swatch and the Casio F-91W. The difference between the movements is covered in the guide to automatic and quartz watches.

The numbers inside the watch

The big makes numbered their watches. Rolex long engraved serial and reference numbers between the lugs, under the bracelet, and Omega numbered its movements; more makes do something similar. The serial number can be looked up in tables that give an approximate year of manufacture, and the reference number shows the model. The numbers are only reliable if the case and movement belong together, so check that they match each other.

The case back may also carry stamps for material and fineness. Gold and silver cases have hallmarks, in Switzerland from the 1880s, and in some countries date letters; see the guide to silver hallmarks for how these are read. Digital watches have a module number on the case back, which reveals the model, and authorised service centres can often confirm when a watch was delivered.

Date markers in brief

A few dates go a long way as guideposts. The Cartier Santos of 1904 and the Tank of 1917 mark the men’s wristwatch; Rolex’s waterproof Oyster came in 1926 and the automatic rotor in 1931. After the Second World War came date windows, diver’s watches such as the Submariner in 1953 and chronographs such as the Speedmaster in 1957. The quartz watch came in 1969, digital watches in the 1970s, the Swatch in 1983 and the Casio F-91W in 1989.

A detail that is newer than one of these dates sets a limit: a date window, a rotating diver’s bezel or a battery cover cannot exist on a watch older than the technology. The guides to the Seiko Astron and the quartz crisis and the Casio F-91W tell how the quartz watch changed both watches and the watch industry.

Original parts, service parts and reissues

An old watch has almost always been serviced, and in a service the crown, crystal, hands and sometimes the dial are often replaced. Service parts can be newer than the watch and change how it looks. A vintage watch is therefore judged by how well its parts fit together: the same ageing on hands and dial, the right case for the movement and numbers that agree.

Many makes have reissued their classic models with modern details: sapphire crystal, newer movements and laser-engraved case backs. A newer interpretation of an older watch can be almost identical in a photograph but differ in size and details. The guides to the Rolex Submariner, the Omega Speedmaster and the Cartier Tank show how the models have changed, and the page on watches and clocks has the history of timekeeping and the models in chronological order.

How to recognise it

Exercise

A watch has a battery cover in the case back and a seconds hand that jumps once a second. What is the earliest possible date of manufacture?