The unique Middle window Seikomatic~

This Seikomatic Ref. 6206-8040 is a remarkable timepiece that embodies Seiko's ingenuity and elegance. Introduced in the early 1960s, the Seikomatic line represented the pinnacle of Seiko’s automatic watch production. This 36mm gold plated beauty features a rare middle day window and a luxury 26-jewel movement, a testament to Seiko’s confidence in their automatic technology, eliminating manual winding altogether. The crown discreetly positioned at 4 o'clock adds to its sleek design. With its Dolphin case back, new strap, and fine tuned to correct time accuracy, this Japan-made vintage watch is a rare collector's dream.

<History>

The first models were time-only watches, based on the Seikosha 603 calibre and date only watches (Seikomatic Self Dater and Slimdate), based on the Seikosha 394, 395 and 840. The famous “Weekdater”, with day and date display was introduced in 1963 with the Seikosha 400 calibre. These first couple of years, the name Seikomatic was treated like a brand. The Seiko logo wasn’t present on the dials (see pictures below).

Evolutions, variations
The range has been then (ca 1965) splitted in sub ranges : Seikomatic (62xx movements), Seikomatic-R (83xx movements), Seikomatic-P (51xx movements) and the name Weekdater disappeared.

From 1964 on, the reference at the back follows the generic Seiko rule : Calibre ID – Case ID (ex : 8305-8000). The same calibre/case combination can have different dials (slightly different writings for ex), different hour markers, different hands and different inner and outer bezels (regular, fluted). Before (and at the beginning of) 1964, the reference on the caseback refers to the case and follows this scheme : JXXXXX (for example J14001).

The final years
In 1967, the Seikomatic name is abandoned and replaced by Business for the 6206 movement (the cases remained the same, with the same references) and Business-A for the 8305/8306 movement. In 1968, the Seikomatic-P becomes the Presmatic (calibres 5106 and 5146) and is sold at least until 1970. P and Presmatic refers to the date quickset which is triggered by pressing the crown, which had a star shape. The Presmatic range remains quite rare.
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The Seikomatic, Business and Presmatic Ranges (ca 1961-1971) | Watch & Vintage