Seiko Galaxy Quartz Ref. 5Y31-5160 – July 1989 – Cushion Case with Guilloche Dial

A cushion-shaped case, a dial whose fine guilloché pattern refracts light in waves—and at 12 o'clock, the emblem of a Seiko line that hardly anyone knows.

The case back bears the inscriptions SEIKO, BASE METAL, ST. STEEL BACK, the reference 5Y31-5160, and the serial number 978693. Above the 12 o'clock marker, the dial features the applied signet of the Galaxy line.

The Galaxy Line

Galaxy was an upscale dress line within the Seiko quartz program, offered primarily in the late 1980s and early 1990s. It is characterized by flat cases, predominantly gold-toned, intricately structured or guilloché dials, classic two- or three-hand styling—and that very emblem at 12 o'clock.

Information on the Galaxy line is significantly scarcer than on King Seiko, Grand Seiko, or Credor; consequently, the line is not very prominent among collectors. In addition to this reference, models such as the 5Y39-7010, 5Y91-5010, V701-1K00, and V701-6K90 have been identified as part of the Galaxy line.

A clarification, as confusion is common: The Galaxy emblem strongly resembles the contemporary Credor signet, and the two are regularly confused in collector circles. This watch is not a Credor, but a Seiko Galaxy. We state this explicitly to avoid any ambiguity, both at the time of purchase and later on.

Cushion Shape and Guilloché

The 1980s were the decade of the flat quartz watch in Japan. Competition shifted from movement engineering to design—resulting in case and dial shapes one would not expect from a watch in this price range.

The cushion shape is one such example: neither a circle nor a rectangle, but a square with softly rounded corners that appears broader on the wrist than it measures, while remaining just 5.7 millimeters thick.

The second is the dial surface. Instead of a smooth lacquer, the dial features a fine, uniform relief structure that reflects light in narrow bands. Such guilloché surfaces originate from classical watchmaking and were machine-applied here to a mass-produced watch—resulting in a dial that continuously changes as the wrist moves.

Design

Slender, applied baton indices sit on the guilloché surface at all twelve hours. The hands are long and delicate; there is a seconds hand, rendered as a thin line.

Above the 12 is the applied Galaxy signet, with the inscription SEIKO QUARTZ below it. The dial bears no further text.

The cushion-shaped case is finished in gold-tone throughout, with a narrow polished bezel framing the dial area. The lugs are designed as curved bars, giving the watch its characteristic silhouette. It comes on a new light brown leather strap with a crocodile grain.

Please note: The case back indicates that the casing is base metal with a stainless steel back. The gold-toned finish is a plating.

Dating

The serial number 978693 dates the watch to July 1989 according to the standard Seiko system. The first digit represents the year, the second the month.

Condition and Provenance

The watch originates from a Japanese watch specialty store and was inspected there prior to sale.

The dial is in very good condition: the guilloché pattern is complete and uniform; there are no spots, the indices are secure, and the hands are undamaged.

Signs of wear are present on the case and should be explicitly noted: the gold-toned plating is rubbed off in places on the edges of the bezel and the lugs; the darker base material is visible in these areas. The crystal shows fine scratches. The case back is brushed and features fine scratches while the inscription remains fully legible.

The leather strap is new and unworn.

The actual condition is shown unretouched in the product photos.

Technical Specifications

• Brand: Seiko
• Model line: Galaxy
• Reference: 5Y31-5160
• Serial number: 978693
• Production date: July 1989
• Movement: Seiko caliber 5Y31, quartz
• Functions: Hour, minute, second
• Case: Base metal with stainless steel back, gold-toned, cushion shape
• Dimensions without crown: 29.7 × 29.5 mm
• Height: 5.7 mm
• Lug-to-lug: 36.5 mm
• Lug width: 19 mm
• Weight incl. strap: 23 g
• Dial: gold-toned, guilloché, with applied baton indices and Galaxy signet at 12 o'clock
• Strap: new light brown leather strap with crocodile grain
• Provenance: Japan

Who is it for?

For Seiko collectors who collect outside the well-known lines—Galaxy is documented but little explored, and those who seek it rarely find anything. For those who want a dial that plays with the light and accept visible signs of wear on the case in return. And for slender wrists.

Warranty (used)

This is a used item. The limitation period for claims for defects under the statutory warranty is 12 months from delivery. The above-described abrasion of the coating is agreed upon as a condition of the item.

Water Resistance Notice

Water resistance is not guaranteed. To protect the movement, the watch should not come into contact with water or moisture.