Rare find: Omron MM38 “Moonphase Diver” – Japan, circa 1980s

An extremely rare Japanese diver's watch with an unusual moon phase display by Omron Japan , model MM38 , manufactured in the early 1980s. This watch uniquely combines technical functionality (20 BAR water resistance) with an astronomical complication – a combination that is extremely rare even among vintage diver models.

The timepiece offered here is in good, fully functional condition with visible signs of wear on the glass and bezel, but is technically flawless and fully wearable.

Background: Omron and the short era of wristwatch production

The Japanese company Omron Corporation (オムロン株式会社), founded in 1933 by Kazuma Tateishi in Kyoto, is now known worldwide as a manufacturer of electronics and medical technology – for example, for blood pressure monitors, sensors and automation systems.

In the late 1970s and early 1980s, Omron attempted to capitalize on the success of the Japanese watch industry and launched a small series of quartz wristwatches under its own name. These were manufactured using "Japan Mov't" technology and presumably produced in cooperation with Japanese OEM suppliers (including Hattori/Seiko Instruments or Citizen Components).

The Omron watch line, however, remained active for only a few years. Due to a focus on metrology and electronics, Omron soon ceased production. Very few models have survived – most bear simple references such as MM38 or MM39 , and their production numbers are minimal.

This model, the Omron MM38 , is one of the most extraordinary designs, as it combines the technical robustness of a diver's watch (20 bar) with a decorative moon phase display – a concept that is almost never found in professional diver's watches.

Design and features

The dial is white with contrasting black indices and a prominently placed moon phase complication at the top. The semicircular window displays a blue starry sky with a golden moon and twinkling stars – a graphically striking detail that lends the watch a poetic character despite its practicality.

The hour markers are applied and feature luminous dots, the hands are black and silver with luminous material. The bidirectional rotating bezel is gold anodized, has black minute scales, and shows clear signs of wear – an honest vintage patina.

The stainless steel case has classic proportions and measures 35.6 mm in diameter (excluding the crown) with a height of 9.9 mm and a lug-to-lug distance of 43.3 mm . It weighs 49 g including the strap. With an 18 mm lug width , the watch is versatile and easy to style – it comes here with a black rubber strap that emphasizes its sporty character.

The engraving on the screwed-on case back reads:
“OMRON MM38 JAPAN – WATER 20 BAR RESIST – ALL STAINLESS STEEL”

The movement is a Japanese quartz caliber with central seconds display and date mechanism, precise and robust, typical of early Omron watches.

Rarity and collector value

Diver's watches with moon phase displays are generally an absolute rarity. In the history of watchmaking, there have been few attempts to combine these two worlds – professional diving technology and astronomical complications. Models like the Omron MM38 are therefore among the most curious and rarest vintage diver's watches from Japan .

Presumably, only a very small number of these models remain worldwide, and of those, probably only a vanishingly small number are outside of Japan.

For collectors of Japanese microbrands and experimental designs from the early quartz era, the MM38 is a coveted and hard-to-find collector's item.

Technical data

• Brand: Omron (Japan)
• Model: MM38
• Caliber: Japan Quartz
• Functions: Hour, minute, second, moon phase
• Water resistance: 20 BAR (200 m)
• Housing: Stainless steel, screwed-on base
• Diameter (excluding crown): 35.6 mm
• Height: 9.9 mm
• Lug-to-lug: 43.3 mm
• Lug width: 18 mm
• Weight: 49 g (including strap)
• Dial: White with moon phase display
• Bezel: Gold-colored anodized, bidirectional rotating
• Strap: Black rubber strap (more recent)
• Case back: Engraved “Omron MM38 Japan – Water 20 BAR Resist”

Condition description

Noticeable signs of wear, especially on the crystal and bezel (scratches, minor abrasions), but overall in good, honest condition. Dial in very good condition, hands clean, movement functional. For collectors who appreciate authenticity, a charming vintage watch with patina and character.

Notice / Warranty

Warranty (used)
This is a used item. The limitation period for claims based on defects (statutory warranty) is 12 months from delivery.

Notice
As this is a vintage watch, water resistance cannot be guaranteed. To protect the movement, the watch should not come into contact with water or moisture.