When the Caliber 9S debuted in 1998, it ushered in a new era of Grand Seiko mechanical watchmaking. An entirely new movement, Caliber 9S was designed from scratch to deliver the high precision and excellent durability for which Grand Seiko was already renowned. It became the platform on which all Grand Seiko mechanical watches would be built, giving rise to a full series of movements with different functions, escapements, and complications. These include the revolutionary Caliber 9SA5 with its Dual-Impulse Escapement and Grand Seiko’s first mechanical chronograph, the Tentagraph. And, of course, there have been GMT watches in a diverse range of styles, including several timepieces with Hi-Beat movements.

To celebrate 25 years of Caliber 9S mechanical watchmaking, Grand Seiko is releasing two new GMTs in its Sport and Elegance Collections, each drawing inspiration from the skies over Mt. Iwate in Iwate Prefecture, where all Grand Seiko mechanical watches are hand-assembled by skilled craftsmen and women.

The new Sport Collection GMT watch features a dial that illustrates the sea of clouds rarely seen at daybreak, when still, humid air forms dense clouds that overlap with one another to create a beautiful tapestry. The blue color is inspired by the sky over Mt. Iwate, the peak visible from the Grand Seiko Studio Shizukuishi, when it is blanketed by this sea of clouds.

The clear sapphire crystal case back, meanwhile, provides an invitation to view a titanium oscillating weight, which has been made a light shade of blue through an anodic oxidation process.* This marks the first time that a Grand Seiko mechanical watch with water resistance to 20 bar has featured an exhibition case back. A rotating bezel with sapphire crystal in blue and white elevates the design while allowing for a total of three time zones to be read at once. And of course, a tried-and-trusted 9S mechanical movement powers the new creation. In this case, it is the Hi-Beat GMT Caliber 9S86, which provides stable accuracy thanks to its frequency of 36,000 vph, equal to ten beats per second or 5 Hz.

This anniversary limited edition of 2,000 will be available exclusively from the Grand Seiko Boutique Online starting in September 2023 before availability extends to the Grand Seiko Boutiques and select retail partners the following month.

* Anodic oxidation treatment
A surface treatment in which metals are subjected to electrolysis so as to generate artificially an oxide film. Titanium oxide film produces color according to the light refraction index, enabling the production of different colors by varying the thickness of the oxide film.

With a sunray dial in the beautiful blue tone of the sky as seen from the peak of Mt. Iwate, the other anniversary limited edition adopts a profile from the Elegance Collection. A classic form prevails thanks to this creation’s mirror-finished bezel and case, gently curved lugs with a distortion-free mirror finish achieved through Zaratsu polishing, and a box-shaped sapphire crystal.

The timeless design features a classic profile, yet a see-through case back provides a view of the thoroughly modern 9S66 GMT movement, which has been outfitted with a titanium oscillating weight in Grand Seiko blue colored by the same anodic oxidation treatment. As with all Grand Seiko GMT watches, its ease of use is ensured through the local hour hand, which is independently adjustable so that precision is maintained even when adjusting the time according to one’s travels. And as with the Sport Collection’s limited-edition watch, the tempered blue GMT hand can be aligned to any time zone of one’s choice. The blue 24-hour scale printed on the pale blue sunray dial displays the second time zone, ensuring that subtlety and legibility distinguish this anniversary edition’s design in equal measure.

A limited edition of 1,700, the watch will be available at the Grand Seiko Boutiques and select retail partners worldwide beginning in October 2023.

Reference	:	SBGJ275
Limited edition	:	2,000 pieces
Movement	:	Caliber 9S86 Automatic driving system
Frequency	:	36,000 vibrations per hour (10 beats per second)
Accuracy	:	-+5 to –3 seconds per day (mean daily rate)
Power reserve	:	55 hours
Hand	:	GMT
Jewels	:	37
Case	:	Stainless steel
Glass	:	Dual-curved sapphire crystal with anti-reflective coating
Case back	:	See-through screw
Water resistance	:	20 bar
Magnetic resistance	:	4,800 A/m
Diameter	:	44.2 mm
Thickness	:	14.8 mm
Bracelet	:	Stainless steel
Buckle	:	Three-fold clasp with push-button release
Price	:	8,600 €

Reference	:	SBGM253
Limited edition	:	1,700 pieces
Movement	:	Caliber 9S66 Automatic driving system
Frequency	:	28,800 vibrations per hour (8 beats per second)
Accuracy	:	-+5 to –3 seconds per day (mean daily rate)
Power reserve	:	72 hours
Hand	:	GMT
Jewels	:	35
Case	:	Stainless steel
Glass	:	Box-shaped sapphire crystal with anti-reflective coating
Case back	:	See-through screw
Water resistance	:	3 bar
Magnetic resistance	:	4,800 A/m
Diameter	:	39.5 mm
Thickness	:	13.7 mm
Bracelet	:	Stainless steel
Buckle	:	Three-fold clasp with push-button release
Price	:	6,300 €