Vintage Seiko Pendant Watch – Green Faceted Crystal Manual from the Mid-1970s

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.

About the Pendant Watch Line

By the late 1960s Seiko was making far more than wristwatches. Alongside its dress and sports lines, the company produced a range of pendant watches — small manual-wind timepieces cased as jewelry and worn on a neck chain rather than the wrist. They were aimed largely at women, sold as an elegant alternative to a wristwatch: a watch you wore as a necklace.

The formula was simple and refined. A slim hand-wound movement — here the 17-jewel 11-series caliber — sat in a compact case, with the crown and hanging bail combined at the top so the whole piece hung cleanly from its chain. Freed from the need to house an automatic rotor or a wrist-side crown, the cases could be kept thin and the backs plain, leaving the front free for decoration. Seiko finished many of these pendants with intricately engine-turned, diamond-cut or faceted-glass fronts — patterns cut directly into the metal or the crystal — so that the watch read first as a piece of jewelry and second as an instrument.

Most were plated rather than solid precious metal — “ASGP” (All Seiko Gold Plated) for the yellow versions, white-gold-plated for the silver-toned ones — which kept them affordable while giving the bright, formal look the style called for. They were popular gifts through the 1970s and, being small and easily set aside, complete surviving examples on their original chains are far less common today than the wristwatches of the same era.

About This Watch

This is a Seiko pendant watch, reference 11-3710, cased in stainless steel and dating from the mid-1970s — Seiko catalogued the 11-3710 at 12,000 yen in 1975. Unlike the plated pendants that make up most of the line, this one uses a solid stainless steel case, which is why it has survived without the brassing that so often spoils gold-plated examples.

Its defining feature is the glass. The case is a stepped, octagonal emerald-cut shape, and both sides are closed by thick faceted crystals rather than flat ones. The front crystal is tinted a deep bottle green and cut into broad facets that catch the light across the dial, so the Seiko signature and the fine blue baton markers appear to sit somewhere beneath the surface — the watch reads as a cut gemstone first and a timepiece second. The back is the same idea in reverse: a faceted crystal tinted bright turquoise, and it is transparent, so the movement is visible through it. A see-through back on a 1970s Seiko pendant is unusual, and it turns the mechanism itself into part of the jewelry.

Behind that back sits Seiko’s miniature 11-series hand-wound movement, caliber 1100, running 17 jewels. The steel back is stamped STAINLESS STEEL / 11-3710 / JAPAN-B, and the case-maker’s mark R25D is stamped inside the case. No serial number is visible on the case, so this one cannot be date-coded to the month in the usual Seiko way; the reference and the faceted-glass styling place it firmly in the mid-1970s.

It comes complete on a vintage steel chain in a matching bright finish.

Technical Specifications

• Brand: Seiko
• Line: Pendant Watch
• Reference Number: 11-3710
• Movement: Seiko caliber 1100 (11-series), 17 jewels, manual wind
• Serial Number: None visible on case
• Production Date: Circa mid-1970s (no serial number present to date-code)
• Case Material: Stainless steel
• Case Diameter: Approx. 26 mm across the case (excluding bail and crown)
• Dial: Green, beneath a faceted green-tinted crystal; Seiko signature, blue baton markers, “17 JEWELS” text
• Crystal: Faceted green-tinted glass front; faceted transparent turquoise glass back
• Case-back: Stainless steel with faceted transparent turquoise crystal, stamped “STAINLESS STEEL / 11-3710 / JAPAN-B”
• Country of Manufacture: Japan

Condition Report

The green faceted crystal is bright and its facets are crisp, with light surface marks that show under close macro magnification but do not catch the eye at normal viewing distance. Beneath it the dial is clean: the Seiko signature, the “17 JEWELS” text and all of the blue baton markers are intact and sharp, and the slim blue hands are complete and unbent.

The stainless steel case is in good order for its age, with the stepped octagonal facets still sharp and only light handling marks on the flanks. Being steel rather than plated, there is no brassing anywhere. The knurled crown is clean and winds smoothly, and the hanging bail at the top is solid with no play.

The turquoise faceted back crystal is intact and clear enough to see the movement through it. Inside the case there is age-related discolouration and light patina on the case plate around the movement, visible in the open photographs — this is internal and is not visible when the watch is closed and worn.

The chain is vintage, in a matching bright finish, and complete with a working spring-ring clasp. The clasp carries no brand marking, so it is offered as a period-correct vintage chain rather than as a confirmed factory-original Seiko piece.

Watch went through a recent service by a professional watch technician and keeps good time.

Comes complete with vintage steel chain*.

Why Collectors Want This Watch Today

Seiko’s 1970s jewelry watches are collected today for exactly the qualities that kept them out of fashion for decades: they are small, decorative and completely unlike the sports watches the brand is now known for. This one sits at the more interesting end of that group. Stainless steel cases are less common in the pendant line than plated ones, and the combination of a faceted green crystal at the front with a faceted, transparent turquoise crystal at the back is a genuinely unusual piece of design — most pendants of the era have a plain, solid back.

It is also complete and working, which matters more than it sounds. Pendant watches were small, easily set aside in a drawer and rarely serviced, so most surviving examples turn up without their chain, non-running, or both. This one has been serviced, keeps good time and comes on its chain — a piece you can wear as it is rather than one that needs sorting out first.

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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 and Rolex are the only two watch companies considered to be 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.