Tissot serial numbers are typically found engraved on the case back and can often provide information about the production date, particularly on vintage models. For many Tissot watches produced during the 20th century, the serial number follows a sequential system that can be cross-referenced with serial number tables compiled by collectors and historical researchers. These tables, while not always perfectly complete, can often narrow down the production date to within a few years.
The case back of a Tissot watch often displays additional reference numbers beyond the serial, including the case reference and caliber number. The caliber number identifies the movement, which for vintage Tissot models may be a proprietary caliber, while modern models commonly use ETA movements (also owned by the Swatch Group). The case reference can sometimes be used to identify the specific model line and variant.
Modern Tissot watches typically include a comprehensive reference number on the case back that encodes information about the model line, movement type, case material, dial color, and strap type. This reference number, often in a format like 'T137.407.11.041.00', can be looked up on Tissot's website or through authorized dealers. For vintage models without clear reference numbers, collector communities and Tissot's historical archives (the brand maintains a museum in Le Locle, Switzerland) may be valuable resources.