Hamilton case backs vary significantly between the vintage American era and the modern Swiss era. Vintage Hamilton watches often feature case backs stamped with the case manufacturer's information, metal quality marks (such as '14K GOLD FILLED' or '10K ROLLED GOLD'), and sometimes the Hamilton name. The case back material and markings can provide important information about the watch's era and quality grade, though it is worth remembering that cases and movements were often treated as separate components during the American era.
Modern Hamilton case backs typically feature the Hamilton 'H' logo, the full brand name, the model reference number, caliber designation, water resistance rating, case material, and 'SWISS MADE' marking. Some models feature exhibition case backs with a sapphire crystal window showing the movement. The presence and style of specific markings can help identify the model line and approximate production period.
Hamilton military watches, which are highly sought after by collectors, carry specific military markings that can include government contract numbers, military specification numbers, and other official designations. These markings vary depending on the military branch, country, and era. Given the high collectibility of military Hamilton watches, case back markings are particularly scrutinized, and collectors are commonly advised to verify military markings carefully, as reproduction military-marked cases do exist.