Seiko Seikomatic Slimdate 'Serviced' 840990 (1963)

Presented for auction by Second Vintage A beautifully preserved example of Seiko's slim automatic dress watch, the Slimdate is a sought-after model appreciated for its elegant proportions and high-quality movement. Finding one from this era with such a pristine dial is uncommon, making this a highly attractive acquisition for enthusiasts of mid-century Japanese design. Brand: Seiko Model: Slimdate Reference Number: 840990 Serial Number: 300223 Movement: Seikosha caliber 840, automatic, 30 jewels Dial: Silver sunburst finish with applied gold-tone faceted indices Case Size: 37 mm (excluding the crown) Case Material: Gold-plated Production Year: 1963 Condition: Excellent vintage condition. Movement serviced on 26 September 2026. Timegrapher: -20-22s/day, running strong and steady. Dial and Hands The pristine and highly legible dial features a striking silver sunburst finish complemented by applied gold-tone faceted indices and a neatly framed date window. The printing remains crisp, with no visible staining or damage present on the surface. Sharp and matching the dial furniture, the gold-tone dauphine hands display clean surfaces with no visible oxidation. Case and Crystal The well-preserved gold-plated case presents an elegant slim profile, retaining sharp lugs and honest wear. Light surface scratches are visible across the gold-tone finish, extending to the thin integrated bezel, which shows wear consistent with the rest of the case. The plain polished caseback exterior remains clean. Maintaining the clean silhouette, the crown is partially recessed at the four o'clock position. A domed acrylic crystal protects the dial, remaining clear with only minor surface dust or light marks. Movement Inside beats the high-jewel Seikosha caliber 840 automatic movement. Visual inspection reveals clean plates and a clean rotor with no visible corrosion, though minor marks are present on the screw heads. The movement bears crisp engravings reading SEIKOMATIC, 30 JEWELS, SEIKOSHA, and 840. Recording -20-22s/day on the timegrapher, it is performing well within expected vintage tolerances; running strong and steady. The movement was serviced on 26 September 2026. Strap The watch is fitted with a complementary black leather strap featuring a crocodile pattern. The strap shows light wear. Condition Excellent vintage condition. The movement was serviced on 26 September 2026 and, supported by the recorded timegrapher result, is running strong and steady. The gold-plated case remains well-preserved with a sharp lug profile, displaying honest wear and light surface scratches. The silver sunburst dial is remarkably pristine, showing no visible damage or staining, while the matching hands remain clean. The domed acrylic crystal is clear, exhibiting only minor surface dust or light marks. Dimensions The case size is 37 mm (excluding the crown). Remarks This Slimdate excels through its exceptionally clean silver sunburst dial and elegant, slender case geometry. Powered by the sophisticated 30-jewel caliber 840, it represents a refined and highly wearable piece of mid-century Japanese watchmaking. History Introduced in 1963, the Slimdate arrived as a thin, date-equipped addition to the Seikomatic family. To achieve its slender profile, the watch is powered by the caliber 840, a 30-jewel automatic movement designed specifically at Seiko's Suwa factory to allow the watch to sit thinner on the wrist compared to standard Seikomatics. Featuring Diashock protection and beating at 18,000 vibrations per hour, the movement relies entirely on automatic winding. The case design incorporates a recessed crown at the four o'clock position, a signature detail that maintains the clean, unbroken lines of the silhouette. During Seiko's mid-1960s reorganization, the sophisticated caliber 840 was subsequently renumbered to the 8305. Payment and Shipping Payment must be completed within 1–3 days after purchase. Your watch will be professionally and securely packaged, then shipped with tracking and insurance for your peace of mind. We use fast express shipping, with typical delivery within 1–4 business days, depending on the destination. Please note that vintage watches may show minor signs of wear, aging, or imperfections, which are considered normal for watches of this age. We kindly ask you to review all photos carefully before bidding. We photograph each watch from multiple angles to provide the most accurate representation possible, and the photos form an important part of the description. The timegrapher assessment if provided is seen as an indication of the movement’s condition under fully wound testing conditions. As with all vintage watches, results may vary in daily use. If you have any concerns regarding functionality or defects after delivery, please contact us within 3 days of receiving the watch so we can assist you. As with all used watches, water resistance is not guaranteed. If you have any questions, feel free to contact us after the auction ends. / Second Vintage SKU: SEI-SJX-0019