Dating a Casio watch is often most effectively accomplished by identifying the model reference number and looking up its known production period. Casio's product catalogs, both official and those compiled by collectors, are commonly available online and can provide information about when specific models were manufactured and sold. The G-Shock community, in particular, maintains extensive databases of model releases and production dates.
Some Casio watches include a date code on the case back or inside the battery compartment that can indicate the manufacture date. This code may follow various formats depending on the era and factory. For quartz analog models, the date code might be stamped on the case back, while for digital models, it may be found on a label inside the battery compartment or on the module itself.
The module number can also help with approximate dating, as specific modules were introduced at known points in time and may have been phased out and replaced by newer versions. For example, the 3229 module used in certain G-Shock models is associated with a specific production era. Collector resources and Casio enthusiast forums are often the best sources for detailed production date information.