CASE MARKINGS
Watch cases often carry markings that are hidden between the lugs, on the inner case back, or along the case side. These can include model reference numbers, hallmarks indicating precious metal content, case maker stamps, and patent numbers. These markings are particularly important for identifying vintage watches where the case back engravings may have worn away over time.
Case Reference Number
A manufacturer-assigned reference number identifying the specific watch case design, dimensions, and material. This is the primary identifier for sourcing correct case parts and compatible accessories.
Lug Width Marking
A number stamped between or on the lugs indicating the distance between them in millimeters. This measurement determines which strap or bracelet width fits your watch.
Bezel Insert Code
A code identifying the specific bezel insert installed on a watch, typically relevant for dive watches and GMT models. This number is essential for sourcing correct replacement inserts.
Crown Logo Stamp
A brand logo or emblem stamped or engraved on the watch crown. This identifies the manufacturer and can indicate whether the crown is an original or replacement part.
Case Size Indicator
A marking indicating the watch case diameter or dimensions, typically in millimeters. This helps identify the watch model variant and determine strap compatibility.
JDM Model Reference Code
A model reference number specific to the Japanese domestic market that differs from the international version. JDM codes often follow unique formatting conventions, such as Seiko's alphanumeric SBDC or SARB prefixes.
Advertisement