Description
Seiko vintage mechanical watch
MADE IN JAPAN
“Seiko” (精工) is a Japanese word meaning “precision,” “exquisite workmanship,” or “refined craftsmanship.” It comes from the characters:
精 (sei) – fine, precise, refined
工 (ko) – craft, workmanship
Originally, Seiko’s watchmaking division was called Seikosha (精工舎), meaning “House of Precision.” The name first appeared on a watch dial in 1924, shortened from Seikosha and keeping the core meaning; the company itself was renamed Hattori Seiko in 1983 and Seiko Corporation in 1990.
So the brand name literally ties directly to the idea of precision engineering—which is exactly what the company wanted to be known for in its watches.
Seiko Business-A
The Seiko Business-A appeared during 1967 as the successor to the Seikomatic-R, the two names overlapping for a time — Seiko’s slim, sophisticated dress watch for the emerging Japanese salaried professional.
The Business-A carried the Seikomatic-R’s formula forward with the refined 8306 caliber — a 30-jewel automatic with Diashock shock protection at 18,000 bph — updating the aesthetic for the new decade. The name stated the purpose plainly: “Business” for the white-collar audience, “A” for automatic. This was the dress watch of Japan’s post-war business generation.
About This Watch
This is the Seiko Business-A ref. 8306-8020. Its case back is stamped for both of the calibers Seiko fitted to this case — 8306/46-8020 — and the dial’s “Diashock 30 Jewels” is what identifies this one as the 30-jewel caliber 8306, automatic with manual wind. Silver/champagne sunburst dial, applied baton indices with aged lume inserts, sword hands. Day-date aperture at 3 o’clock, with a bi-directional quickset date; the day advances by cycling the hands past midnight. Stainless steel case with original-style steel expansion bracelet.
(*) Steel expansion bracelets are often shortened by previous owners. Check the bracelet size in the product images before purchasing.
This watch ships from 🇺🇦 Ukraine with tracking number
| Brand | Seiko |
| Line | Business-A |
| Reference | 8306-8020 (case back stamped 8306/46-8020, for both calibers) |
| Movement | Caliber 8306, Automatic + manual wind |
| Jewels | 30 |
| Shock protection | Diashock |
| Frequency | 18,000 bph |
| Complication | Day-date at 3 o’clock — quickset date, day set by cycling the hands |
| Case | Stainless steel, approx. 35 mm excluding crown (41.5 mm lug-to-lug, 18 mm lug width) |
| Crystal | Acrylic |
| Dial | Silver/champagne sunburst, applied baton indices with aged lume inserts |
| Bracelet | Steel expansion (original style) |
| Country | MADE IN JAPAN |
| Era | ~1967–1969 |
CONDITION REPORT
The watch is in good vintage condition with light wear appropriate to its age.
- Dial: Clean, with the lume inserts in the baton indices and hands aged to a warm cream. No moisture intrusion or major damage visible.
- Case: Light surface scratches consistent with decades of wear.
- Crystal: Acrylic — minor surface marks visible at certain angles.
- Bracelet: Intact and functional with age-appropriate patina.
This watch has recently been serviced by a professional watchmaker and keeps good time.
Why Collectors and Enthusiasts Want This Watch Today
The Seiko Business-A occupies a fascinating position in the vintage Seiko hierarchy — above the Seiko 5 but below the King Seiko, offering a genuine 30-jewel automatic in a restrained dress case.
The 8306 caliber impresses: 30 jewels when most mid-market automatics offered 17–21, with Diashock protecting the balance staff through decades of daily wear. The day-date at 3 adds practical utility without cluttering the dial, and the date is quickset in both directions.
What makes this example particularly appealing is the presence of the original expansion bracelet. The silver sunburst dial has aged evenly, with the lume inserts mellowed to a warm cream.
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We guarantee the item you receive looks and works exactly as advertised — or your money back.
Seiko lug-width matched leather straps — 18 / 19 / 20 mm
About the watch factory
Seiko Group Corporation (セイコーグループ株式会社), commonly known as Seiko, is a Japanese maker of watches, clocks, electronic devices, and semiconductors. Founded in 1881 by Kintarō Hattori in Tokyo, Seiko introduced the world’s first commercial quartz wristwatch in 1969.
Seiko is one of the few watch companies that is fully vertically integrated. Seiko is able to design and develop all the components of a watch, as well as assemble, adjust, inspect and ship them in-house.
Seiko offers one of the widest ranges of watch technologies in the world—quartz, kinetic, solar, mechanical, and Spring Drive—spanning everything from affordable everyday pieces to six-figure haute horlogerie. Its global lineup now includes Grand Seiko, King Seiko, Prospex, Astron, Presage, and Seiko 5 Sports.
