King Seiko 56KS Hi-Beat Ref. 5621-7000 - Navy Blue Roman Numeral Dial, December 1970
At first glance, the dial of this King Seiko might appear black. However, when light hits the surface, a deep navy blue tone emerges, and the large metal Roman numerals seem to stand out distinctly from the dial. The Ref. 5621-7000 represents a unique take within the 56KS family distinct from the typical baton-indexed models by blending the modern Japanese case geometry of the 1970s with a classic dress-watch aesthetic.
**IMPORTANT NOTE: As this item ships from within the European Union, you will not be liable for customs duties within the EU.**
This combination is not a later modification; the dark blue, Roman-numeral 5621-7000 listed in Seiko’s Japanese catalogs of the era under the code 56KA 024 was originally offered with this exact design. The code "JAPAN 5621-7010T" at the bottom of the dial is also consistent with this configuration. The numerals are not printed but are metal indices applied to the surface; this is why they appear as a distinct layer against the dark dial as the light shifts.
The serial number "0D0550" on the case back dates the watch to December 1970. The 56KS holds a special place in King Seiko history; developed by Suwa Seikosha, this family represents the brand's era of automatic, high-frequency movements. Inside, the 25-jewel Calibre 5621A features automatic winding with manual winding capability, a hacking function (stop-seconds), and beats at 28,800 vibrations per hour. The "HI-BEAT" inscription on the dial refers not to a 36,000 vph rate, but to the high-frequency "8-beat" architecture characteristic of that era.
One of the 5621’s most significant contributions to this dial is actually a feature it lacks: a date window. Unlike its siblings, the 5625 and 5626, the 5621 has no calendar function. Consequently, the large Roman numerals remain uninterrupted from XII to VI, forming a complete ring around the deep navy blue dial. Here, the no-date layout is not merely a technical choice; it is a design decision that defines the entire character of the dial.
The case is not a standard screw-back construction, either. Due to its monocoque body, the movement is accessed via the crystal rather than the case back; the "OPEN THRU GLASS" inscription on the back serves as a direct instruction for servicing. Measuring approximately 35.5 mm in diameter, the cushion-shaped case—featuring broad brushed upper surfaces, a polished bezel, and soft, flowing shoulders—has a commanding presence on the wrist that belies its modest size. The contrast between the classic Roman numeral dial and this modern case design is a key factor that sets the watch apart.
This particular example shows light signs of wear consistent with its age; however, the brushed texture, case geometry, and surface transitions remain crisp and well-defined. The KS-signed crown and the gold-toned King Seiko medallion on the case back are also remarkably well-preserved. The watch is fitted with a new brown leather strap and comes with a period-correct Seiko presentation box.
Final Thoughts
What makes the 5621-7000 memorable is not just its navy blue dial, but the way it harmoniously blends two distinct design languages within a single timepiece. On the outside, it features the broad, modern cushion case typical of the 1970s; inside, there is a classic dial defined by uninterrupted applied Roman numerals. Dating to December 1970, this 56KA 024 is an exceptional King Seiko that conveys the automatic Hi-Beat engineering of the 56KS series—relying solely on its proportions and dial rather than ostentatious display.
The item shown was manufactured in 1970.
PROFESSIONALLY FULLY SERVICED.
The movement was completely disassembled; every part was cleaned, lubricated, and precision-adjusted to ensure flawless operation. (It will not require further servicing for three years, provided it is not exposed to adverse conditions.)
Item Condition: Tested; all functions are fully operational.
