Watch Reference Numbers Explained: How Top Brands Code Their Watches

What is a Reference Number?

A reference number (or model number) is the manufacturer's unique code for a specific watch design. It defines the case, dial, material, and sometimes the movement.

Rolex

Modern Rolex references are typically 6 digits (e.g., 126610). The first 2–3 digits identify the model family (Submariner, Datejust, Daytona, etc.), while the last digits and suffix letters indicate materials and bezels.

• Model family: 124xxx = No‑date Submariner, 1263xx = Datejust.
• Suffix letters: LN = black bezel, LV = green bezel, LB = blue bezel, CHNR = two‑tone ceramic "Root Beer" GMT bezel.

Patek Philippe

Patek uses a simpler system, often 4 digits (e.g., 5711). Letters following the number denote material.

• A = steel (acier)
• R = rose gold
• G = white gold
• J = yellow gold

Audemars Piguet

Royal Oak references look intimidating (e.g., 15500ST.OO.1220ST.01) but they follow a logic:

• The first part (15500) is the model family and size.
• Two letters after that indicate the case material (ST = steel, OR = rose gold, PT = platinum, TI = titanium).
• The remaining codes refer to bezel/bracelet type and dial variant.

Omega's PIC Code

Omega uses a long string (e.g., 311.30.42.30.01.005). The first three digits identify the collection (e.g., 311 for Speedmaster), the next two the case/strap material, and the remaining groups describe movement and dial variant.

TAG Heuer

TAG references typically start with two letters for the collection (e.g., WBP = Aquaracer, CBN = Carrera chronograph), followed by numbers that define size, movement, and colorway.

Cartier

Cartier reference numbers can look random, but modern pieces often have short alphanumeric codes (e.g., WSSA0030 for a Santos). The prefix letter usually indicates the product category (watch vs. jewelry) and the following letters/numbers identify the specific design.

Breitling

Breitling uses reference structures like AB0121211C1A1. The first letter(s) indicate metal (A = steel, B = black steel, R = red gold), followed by numbers for family and movement. The suffix letters/numbers represent dial color and bracelet type.

IWC

IWC references (e.g., IW378003) start with the brand prefix (IW), then digits for the collection and configuration. Watches within the same pilot or Portugieser family will often share the first 3–4 digits.

Jaeger-LeCoultre

JLC model codes are often numeric with a trailing letter (e.g., Q3848422). The first digits refer to the calibre family and case, and the suffix encodes metal and strap.

Seiko & Grand Seiko

Seiko typically uses a movement code + case code pattern (e.g., 7S26-0020). Grand Seiko's modern references (e.g., SBGA211) use prefixes for movement family (SBGA = Spring Drive) followed by numbers for the specific design.

Putting It All Together

When you see a reference number, treat it as a compressed data string about the watch. Use the brand's logic to decode model family, size, material, and generation—then verify it against photos and specifications using tools like watchID and brand catalogues.