Citizen case backs typically display several key pieces of information. The most commonly found markings include the caliber number, serial number, water resistance rating, case material, and country of origin. The caliber number is often particularly useful, as it can be looked up in Citizen's extensive technical documentation to determine the movement type, features, and battery specifications (for quartz models).
Many Citizen case backs also feature model-specific identifiers that can help narrow down the exact reference. Eco-Drive models often include markings indicating the solar charging technology, such as 'ECO-DRIVE' or the Eco-Drive logo. Promaster dive watches typically display prominent water resistance ratings and may include additional certifications. The Citizen logo on the case back has evolved over time, and the style of the logo can sometimes help approximate the production era.
Some Citizen watches, particularly those in premium lines or limited editions, may feature additional case back details such as commemorative engravings, exhibition windows showing the movement, or special finishing. As with all watch brands, case back markings can potentially be altered or counterfeited, so they should ideally be considered alongside other identifying factors such as the movement, dial, and overall build quality when assessing authenticity.