Rolex 16750 was in production approximately from 1981 to 1988, a run of approximately 7 years, carrying the 3075 automatic caliber in a 40 mm case rated to 100 meters.
The transitional: quickset date, doubled water resistance, and early matte dials giving way to gloss with white gold surrounds.
Dates carry a "c." because that is what honesty requires: Seiko's own archive gives only approximate production windows by caliber, so the file states the documented range and marks it as such rather than inventing precision.
The full collector's file for this reference — variants, dial codes, and the authentication walk-through — is on the writing schedule; the specifications above are the permanent record.
GMT-Master fraud follows the family's own geology: on the long-lived vintage references every part has a documented era, and franken watches are assembled across them - gilt dials on late cases, swapped bezel inserts chasing ghost premiums, service dials priced as original. The rules: the serial dates the case and every visible part must belong to that era; bezel inserts swap in minutes and prove nothing; underline and error-dial claims carry the burden of proof; and on the ceramic references, counterfeit pressure is high enough that platform authentication is the sensible route. The Rolex serial lookup on this site covers every reference in this family.
Production windows and specifications compiled from documented collector references and period catalogs, cross-checked across independent sources; manufacturer records for this era are approximate by Seiko's own account.