By the late 1970s and early 1980s, Seiko had the Swiss on the run with the Japanese company’s run of astonishingly accurate – and far less expensive to produce – quartz watches, like this 1981 Grand Quartz Twin Quartz 9940-8000 “Toyo Seikan Group Holdings” quartz dress watch here, on a beads-of-rice stainless-steel bracelet. 
 
During the same era, Seiko added “Twin Quartz” to its high-end Grand and King Quartz watches, like the example here, which referred to its proprietary thermal compensation technology.  Two quartz oscillators were set alongside each other – one used to detect the temperature so variations due to temperature change in the other oscillator could be compensated for.  Completed in 1978, the Twin Quartz movement raised the stakes in the competition for the Swiss to develop the world’s most accurate watches (which a mere decade before had been solely Swiss turf).  
 
But why do we call this Grand Quartz a Toyo Seikan Group Holdings dress watch?
 
Based on the Kanji Japanese engravings on the caseback, this Grand Quartz was awarded in 1983 to a loyal employee of 25 years to the Japan-based Toyo Seikan Group Holdings, Ltd. (東洋製罐グループホールディングス株式会社, Tōyō Seikan Gurūpu Hōrudingusu Kabushiki-gaisha), a company founded in 1917 in Japan that specializes in mainly packaging products (one of the largest in the world), but also includes holdings in engineering, steel manufacturing, real estate, and auto / agriculture concerns.
 
As of 2024, Toyo Seikan – a typical Japanese conglomerate – had $6.2 billion in sales and a presence in Japan, Thailand, China, and Singapore with nearly 20 thousand employees. The firm’s mission statement is, “The strength that underlies our value creation is our capability in monozukuri (Japanese concept of manufacturing, or the art, science and craft of making things), which has been enhanced by the trust we have built with various stakeholders for over a century.”
 
Within the world of vintage Seiko, Grand Seiko – distinguished by the “GS” on dial, and often crown – inhabits the top of the food chain, simple as that. Grand Seiko – with 51 different models – were simply the most painstakingly designed and exquisite watches made by Seiko, produced by both the Dani and Suwa factories.
 
But all this ended with the Grand Seiko 5646 line when production ceased in 1976, a self-inflicted fatality of the Quartz Crisis.  By the time it ended, the GS featured largely automated – rather than hand built – construction, and the 5646 was regarded as one of the best combinations of reliability, precision, and maintenance within the original GS lineup.
 
Or did Seiko really end Grand Seiko?
 
The Quartz Crisis is capitalized for good reason – it had a significant and devastating impact on global mechanical watch making but took several years to build up momentum to hurt Grand Seiko sales numbers, seemingly rendering it a foregone conclusion for Seiko to end its production.
 
By 1975, five years after the Seiko introduction of the game changing Astron, quartz was steadily gaining market share, with the cheapest reference in the catalogue priced at just 32,000 Yen (the legendary 6139 automatic chronograph was a little over half that at 19,000 Yen and the 6105 divers, 20,000).
 
As Seiko transitioned steadily into a solid quartz line up – while atypically keeping some mechanical lines going – Seiko chose to continue mechanical name conventions of its dress watches, namely: Grand Quartz, King Quartz, Lord Quartz, all updated for the new quartz age.
 
Seiko made the strategic move to shift existing King and Grand Seiko brand loyalty away from mechanical and to the King and Grand Quartz lines.  And the rest is history – until, that is, Seiko brought back their mechanical Grand Seiko line up in 1988.
 
But that’s a story for another time…
 
This Grand Quartz Twin Quartz comes on a stainless-steel BOR bracelet, and with nylon strap, rugged travel case, and springbar tool.