1978 Grand Quartz Twin-Quartz 9943-8010

OmegaSeiko · Fri. 9:49am

Final acquisition in my high accuracy Seiko trio was delivered this morning.

Was able to get a great price on this as it had an aftermarket crown. Replacement part was cheap to find and I am hoping my local guy can swap them for a reasonable price.

It uses two quartz oscillators, with one compensating for temp changes. Where a mechanical watch from this era may have 10 seconds variation per day, this watch was rated at +/- 10 seconds per year. Quartz Grand Seiko’s with this accuracy today would cost 10x what I paid for this one.

There are so many cool quartz models out there for reasonable prices. It’s crazy to think what a fine timepiece this would have been back in the day. Getting one in good condition for just a couple hundred bucks seems like a lot of watch for the money. Many had more interesting dials but I really wanted this case design and the twin-quartz feature.

50kopek · 2026-11-02T03:48:54-0600

OmegaSeiko
Final acquisition in my high accuracy Seiko trio was delivered this morning.

Was able to get a great price on this as it had an aftermarket crown. Replacement part was cheap to find and I am hoping my local guy can swap them for a reasonable price.

It uses two quartz oscillators, with one compensating for temp changes. Where a mechanical watch from this era may have 10 seconds variation per day, this watch was rated at +/- 10 seconds per year. Quartz Grand Seiko’s with this accuracy today would cost 10x what I paid for this one.

There are so many cool quartz models out there for reasonable prices. It’s crazy to think what a fine timepiece this would have been back in the day. Getting one in good condition for just a couple hundred bucks seems like a lot of watch for the money. Many had more interesting dials but I really wanted this case design and the twin-quartz feature.

That looks great! Like you, I've gotten a lot more appreciation for these vintage quartz models through the years. The quartz stigma is considerable in (some) watch collecting circles. But back in the day, these were not some cheap plastic watches but top of the line products. As you've pointed out a Grand Seiko with that type of accuracy today would cost a lot more than your watch, but your watch was probably one of Seiko's priciest offerings at the time. In the early 70s when mechanical GS and quartz overlapped, the top end quartz models were considerably more expensive than the mechanical GS.
Another thing I love about these watches is that the Grand Quartz case style is a clear continuation of the mechanical GS case styles and design principles.

OmegaSeiko · 2026-11-02T05:58:59-0600

50kopek
That looks great! Like you, I've gotten a lot more appreciation for these vintage quartz models through the years. The quartz stigma is considerable in (some) watch collecting circles. But back in the day, these were not some cheap plastic watches but top of the line products. As you've pointed out a Grand Seiko with that type of accuracy today would cost a lot more than your watch, but your watch was probably one of Seiko's priciest offerings at the time. In the early 70s when mechanical GS and quartz overlapped, the top end quartz models were considerably more expensive than the mechanical GS.
Another thing I love about these watches is that the Grand Quartz case style is a clear continuation of the mechanical GS case styles and design principles.

Thank you.

I really wanted a quartz from this era to round out the history of my 45KS 36k High Beat and 56KS chronometer. I was drawn to the idea of the twin-quartz concept as almost engineering overkill. Unfortunately, I struggled to pick a favorite from all the available variations. There are so many great models and some have incredible dials that it took me a while to decide. In the end, the case shape of this one won me over.

50kopek · 2026-11-02T08:17:39-0600

OmegaSeiko
Thank you.

I really wanted a quartz from this era to round out the history of my 45KS 36k High Beat and 56KS chronometer. I was drawn to the idea of the twin-quartz concept as almost engineering overkill. Unfortunately, I struggled to pick a favorite from all the available variations. There are so many great models and some have incredible dials that it took me a while to decide. In the end, the case shape of this one won me over.

Good choice. The case looks very similar to that of the 564X-7010, which to me is one of the best looking and best proportioned classic GS grammar of design cases.

Larry S · 2026-11-02T12:02:35-0600

Still feel that a GS quartz is missing from the fleet. This is a beauty.

1978 Grand Quartz Twin-Quartz 9943-8010

OmegaSeiko

50kopek

OmegaSeiko

50kopek

Larry S

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