Vintage 1964 Seiko Seikomatic Slimdate – 30 Jewels in ASGP (Seiko Gold-Plated) Case

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 1997.

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 Seikomatic line overview

The Seiko Seikomatic line was a flagship series of high-quality automatic watches produced primarily throughout the 1960s. It represented Seiko’s transition into the modern era of self-winding timepieces, and sat at the top of the company’s mainstream automatic ranges.

The Seikomatic Line: The “Business Class” Ancestor

Seikomatic was designed for the “modern business professional” of the 1960s. Its most iconic design choice was the recessed crown at the 4 o’clock position. Because the movement was so efficient at self-winding, Seiko believed the wearer rarely needed to use the crown, so they tucked it away to create a sleek, “crownless” silhouette that wouldn’t snag on shirt cuffs.

• The Name: It’s a portmanteau of “Seiko” and “Automatic.” At the time, automatic winding was a high-tech feature, so Seiko branded these watches to highlight that they didn’t need manual winding.
• The Design Philosophy: Seikomatics were designed for the “New Lifestyle” of the 1960s—aimed at office workers and professionals. They were known for having no visible crown (the crown was often tucked away at the 4 o’clock position) to emphasize that the watch was fully automatic and didn’t need to be touched.
• The “Weekdater”: The most famous Seikomatic is the “Weekdater,” which featured a full day-of-the-week window alongside the date at 3 o’clock. This was a massive status symbol for business people in the ’60s.

This April 1964 Seikomatic Slimdate runs the 30-jewel Caliber 840 and carries a silver sunburst dial with applied gold-tone baton indices. Engineered for the 1960s executive, the “Slim” profile and recessed 4 o’clock crown offer a sophisticated silhouette that fits perfectly under a modern dress shirt.

The “Executive” Heritage

Grand Seiko launched in 1960, but it stayed hand-wound until the automatic 62GS arrived in 1966–67. Through the mid-1960s the Seikomatic sat at the top of Seiko’s automatic range. The “Slimdate” variant was a specific technical achievement from the Suwa Seikosha factory, designed to prove that a high-precision automatic watch didn’t need to be bulky.

Technical Excellence: Caliber 840

At the heart of this timepiece is the 30-jewel Caliber 840 (later known as the 8305). While many contemporary watches used 17 or 21 jewels, the 840 carries 30. Its real achievement was height: the 830/840 family trimmed several millimetres off the earlier caliber 603, which is what made the slim Slimdate case possible.

Aesthetic Condition

• Dial: A clean, even silver sunburst dial carrying the gold Seikomatic emblem above the centre and applied gold-tone indices.
• Case: Seiko ASGP gold plating, stamped inside the case back. The outer back is plain apart from the serial, 4407843.
• Crown: Subtly recessed at the 4 o’clock position to emphasize the automatic winding capability.

Detailed Specifications

This watch has recently been serviced by a professional watchmaker and keeps good time.

Condition Note

This is a genuine vintage timepiece from 1964. While the movement is clean and running well, please note that vintage watches are not recommended for water exposure. The gold plating shows light brassing on the high points of the lugs.

Comes with padded leather strap included.

(*)Note: Stock bracelets are often shortened by previous owners and may not fit you(see bracelet size in the product images). We match the strap to this watch’s lug width, so there is nothing for you to measure — just pick a padded leather strap for Seiko from the options at the top of the page.

Modes of payment:

• PayPal
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• bitcoin

We guarantee the item you receive looks and works exactly as advertised — or your money back.

Seiko Group Corporation (セイコーグループ株式会社, Seikō Gurūpu kabushiki gaisha), 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 widely known for its wristwatches. 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’s mechanical watches consist of approximately 200 parts, and the company has the technology and production facilities to design and manufacture all of these parts internally.

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. Over the decades it has launched multiple global brands, including Lorus, Pulsar, and Alba, while elevating its prestige through innovations like Spring Drive, which helped push Seiko into higher-end territory. In the 2010s, Grand Seiko and Credor were separated into fully independent luxury brands, while Seiko’s own global lineup now includes Grand Seiko, King Seiko, Prospex, Astron, Presage, and Seiko 5 Sports, with Credor remaining primarily Japan-focused.

Among Seiko’s key lines, Seiko 5 (born in 1963) is the gateway mechanical series known for durability and value; Lord Matic defined 1970s style with faceted crystals and colorful dials; Astron remains Seiko’s flagship GPS-solar tech line; Presage focuses on traditional mechanical craftsmanship with enamel and urushi dials; and Prospex delivers professional-grade dive, field, and pilot watches often embraced by enthusiasts. At the top end, Grand Seiko emphasizes precision, Zaratsu polished design, and movements like Spring Drive, while King Seiko—revived in the 2020s—brings back sharp, elegant 1960s styling with modern calibres.

Finally, Credor represents Seiko’s pinnacle of artisanal watchmaking, producing low-volume pieces in precious metals and showcasing Japanese decorative arts and haute complications from the Micro Artist Studio. Beyond watches, Seiko has also produced various electronic devices and, historically, jewelry and eyewear—though those divisions have since shifted to other companies.