{"product_id":"seikomatic-r-8305-9010-juli-1965-diashock-30-jewels-water-proof-boden-mit-delfin-revidiert","title":"Seikomatic-R 8305-9010 – July 1965 – Diashock 30 Jewels – \"WATER PROOF\" case back with dolphin – serviced","description":"\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThirty jewels. That is the number that sets this watch apart from the Seikomatic family and is virtually non-existent on Japanese dials of the 1960s outside of the top-tier lines. This example from July 1965 has been fully serviced in Japan—including case restoration.\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eThe Seikomatic family\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eSeiko introduced the Seikomatic line in 1960 with the caliber 603, bringing automatic winding into mass production. From this foundation, an entire family developed over the following years with different levels of technical sophistication, which Seiko denoted with a letter suffix for each.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThe \u003cstrong\u003eSeikomatic-R\u003c\/strong\u003e offered here represents the high-end variant: The caliber 8305 operates with \u003cstrong\u003e30 jewels\u003c\/strong\u003e and Diashock shock protection, and displays the date in addition to the time. For comparison: the brand's quality everyday automatics from this period typically had 17 to 21 jewels; 30 jewels were reserved for more complex constructions.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThe case back bears the engraving \u003cstrong\u003eSEIKO · WATER PROOF · S.S. · 8305-9010\u003c\/strong\u003e with the serial number 5703409, which dates the watch to \u003cstrong\u003eJuly 1965\u003c\/strong\u003e. In the center sits the dolphin emblem, which Seiko used during this era to identify water-resistant cases—a detail not found on later case backs. Furthermore, the designation \"WATER PROOF\" was replaced by \"WATER RESISTANT\" in the years that followed.\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eServiced\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThe watch was fully and professionally serviced in Japan in the spring of 2026.\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eDesign and character\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThe silver dial features a fine sunburst finish and applied, multi-faceted baton indices whose edges flash sharply in angled light. The \"SEIKO\" signature is at 12 o'clock, with \"SEIKOMATIC-R \/ DIASHOCK 30 JEWELS\" below at 6 o'clock. The framed date window is positioned at 3 o'clock.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThe \u003cstrong\u003efinely fluted bezel\u003c\/strong\u003e is a defining feature, giving the dial a structured frame and enhancing the watch visually without making it look overly ornate. Together with the inner rehaut ring, it creates a sense of layered depth that is missing from smooth bezels.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThe stainless steel case measures 37.7 mm without the crown, with a 42.5 mm lug-to-lug distance and a height of only 10.3 mm—exceptionally thin for a 1960s automatic and an ideal everyday size by modern standards. At 47 grams on the new dark brown leather strap, the watch is effortless to wear.\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eCondition\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eCase in good condition after a conservative refurbishment; crystal replaced. A high-quality new Seiko replacement strap has been fitted, which highlights the watch's premium character.\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eTechnical data\u003c\/h2\u003e\n\u003cul dir=\"ltr\" class=\"[li_\u0026amp;]:mb-0 [li_\u0026amp;]:mt-1 [li_\u0026amp;]:gap-1 [\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3 print:block print:space-y-1\"\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eBrand: Seiko\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eModel: Seikomatic-R\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eReference: 8305-9010\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eCaliber: Seiko 8305\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eMovement: Automatic\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eJewels: 30 Jewels\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eShock protection: Diashock\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eFunctions: Hour, minute, central second, date\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eCase material: Stainless steel, case back with \"WATER PROOF\" engraving and dolphin emblem\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eDiameter excluding crown: 37.7 mm\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eLug-to-lug: 42.5 mm\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eHeight: 10.3 mm\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eLug width: 19 mm\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eWeight including strap: 47 g\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eSerial number: 5703409\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eDating: July 1965\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eService: Complete overhaul incl. case restoration in spring 2026 in Japan\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eStrap: New dark brown Seiko-branded leather strap\u003c\/li\u003e\n\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\"\u003eOrigin: Japan\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eFor whom?\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eFor collectors who are systematically building a collection of Seiko’s automatic evolution from the 1960s and distinguishing between the variants of the Seikomatic family. For anyone looking for a vintage automatic with a 37.7 mm diameter and a height of only 10.3 mm—a combination that is rarely produced today. And for buyers who value a documented service with case restoration over an untouched \"barn find.\"\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eWarranty (pre-owned)\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eThis is a pre-owned item. The limitation period for claims for defects (statutory warranty) is 12 months from delivery.\u003c\/p\u003e\n\u003ch2 dir=\"ltr\" class=\"mt-3 -mb-1 text-[1.125rem] font-bold\"\u003eNote\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" dir=\"ltr\"\u003eAs this is a pre-owned watch, water resistance cannot be guaranteed despite the historical \"Water Proof\" engraving. To protect the movement, the watch should not come into contact with water or moisture.\u003c\/p\u003e","brand":"Vintage \u0026 JDM (Japan Domestic Market)","offers":[{"title":"Default Title","offer_id":54176213467474,"sku":"A406","price":629.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0911\/3908\/0530\/files\/BE86CB12-224C-4E06-9C48-96504D4F2462.jpg?v=1785939196","url":"https:\/\/japanese-microbrands.com\/en\/products\/seikomatic-r-8305-9010-juli-1965-diashock-30-jewels-water-proof-boden-mit-delfin-revidiert","provider":"Japanese Microbrands - Mario Lenke","version":"1.0","type":"link"}