Omega replaced their existing 5digit case reference code system in the early 1960s with a new one which was used to identify their various case designs. The code is in the format XXX.XXX(X) and the 3 digit prefix denotes details about the case design, whether it’s a gents/ ladies, waterproof or not and the type of movement it houses, manual or automatic. The 3 or 4 digit suffix denoted the actual model number. This is not to be confused with the watch serial number which is stamped on the movement itself or on the rear cover or lug on later watches (c. 1998 onwards).
The table below denotes the codes for the 3 digit prefix. A Speedmaster Professional for example, would carry the code 145.0022 (1- gents watch/4- manual wind chronograph/5- Water resistant).
|1 – Gent’s Watch||1 – Manual winding without second||1 – Non-water-resistant|
|2 – Gent’s Jewellery Watch||2 – Manual winding small second||2 – Non-water-resistant Calender|
|3 – Gent’s Bracelet Watch||3 – Manual winding centre second||3 – Non-water-resistant chronometer|
|4 – Gent’s Jewellery Bracelet Watch||4 – Manual winding chronograph||4 – Non-water-resistant chronometer calender|
|5 – Lady’s Watch||5 – Self-winding without second||5 – Water-resistant|
|6 – Lady’s Jewellery Watch||6 – Self-winding centre second||6 – Water-resistant Calender|
|7 – Lady’s Bracelet Watch||7 – Self-winding chronograph||7 – Water-resistant chronometer|
|8 – Lady’s Jewellery Bracelet Watch||8 – Electronic chronograph||8 – Water-resistant chronometer calender|
|9 – Electronic|