Seiko's high-accuracy quartz movement line is the 9F series.

Introduced in 1993 with the marketing claim, “quartz that surpasses quartz”, the 9F series boasts precision beyond any other quartz watch. Seiko integrated a number of technical advancements, including a “backlash auto-adjust mechanism”, twin-pulse drivetrain, and an instant calendar change mechanism.

Earlier Grand Seiko quartz movements boasted 10 second per year accuracy, including the 8J, 95 and 3F calibres.

Unique features of the 9F quartz calibre

• A “twin pulse” system gives the movement greater torque, allowing larger and longer hands to be used
• Backlash auto-adjust prevents the hands from vibrating after a power impulse
• The instant calendar change mechanism includes a spring lever mechanism, allowing the 9F calibre to flip the date counter in 1/2,000th second
• The rotor and gear train are sealed in a “cabin”, allowing a claimed service interval of 50 years
• Each of the hands moves on its own independent mechanism, allowing all three to move separately and precisely
• Seiko “ages” each quartz crystal for 3 months before timing it to ensure accuracy
• Calibre 9F includes a temperature sensor which adjusts to changes every 160 seconds
• Caliber 9F has a “Pacing Switch” allowing accuracy to be adjusted

The 9F series was refreshed in 2003 along with the release of an anti-magnetic model.

There are four models in the Seiko 9F quartz family

• 9F61 - Time only
• 9F62 - Date
• 9F82 - Date (updated)
• 9F83 - Day/date

The Seiko 9F calibres are used in the following watches

• Grand Seiko 9F8 Quartz (1993) - “Quartz that surpasses quartz”
• Grand Seiko SBGX Antimagnetic (2003-present) - 9F61
• Grand Seiko SBGX Quartz (1998?-present) - 9F61/62
• Grand Seiko SBGV Quartz Date (1996?-present) - 9F82
• Grand Seiko SBGT Quartz Day/Date (1994?-present) - 9F83
• Grand Seiko SBGN Quartz GMT (2018-present) - 9F86