Seiko case backs typically feature several important markings that can help identify the watch. The most prominent marking is usually the caliber number and case reference, often displayed in a format like '7S26-0010', where '7S26' indicates the movement caliber and '0010' refers to the case design. This alphanumeric code is commonly found engraved or stamped on the outer case back and is often considered the most reliable way to look up the watch's specifications.
Additional case back markings on Seiko watches often include water resistance ratings (commonly expressed in bars or meters), the country of assembly, and material indicators such as 'STAINLESS STEEL' or 'ST. STEEL'. Many Seiko case backs also display a logo, which has evolved over the decades. Vintage models may feature the 'Tsunami' wave symbol, the Suwa or Daini Seikosha factory marks, or the classic Seiko shield emblem. The presence and style of these logos can sometimes help narrow down the production era.
On higher-end models, particularly Grand Seiko, the case back may include additional markings such as the lion medallion, the 'GS' insignia, and more detailed finishing. Some limited-edition pieces feature exhibition case backs with the decorated movement visible. It is important to note that case back markings can potentially be altered or replaced, so collectors are typically advised to verify markings against known references and, when possible, inspect the movement for consistency.