Updated: Sep 6, 2020
The Lord Marvel (LM) introduced in 1958 was Seiko’s first high end luxury watch model and with the subsequent release of the Grand Seiko First (GS1st) in 1960 (both produced by Suwa Seikosha), this marked Seiko’s announcement to the domestic market in Japan that they were ready to compete with the Swiss in the high end segment. However, it wasn’t just the LM and GS1st that were offered as Seiko’s top quality watches. When one observes closely, we see a pattern of a certain logo on the dial that signified a high degree of craftsmanship and prestige - the Special Dial logo above the six o’clock.
What is “Special Dial” and the “shokuji” index ?
The Special Dial logo is an octagonal sun shaped logo printed above the six o’clock index on the dial. Often referred to as the SD logo, this logo signifies that the index of the dial is made of either 18k or 14k solid yellow gold (or 14k white gold for stainless steel cased watches).
The concept of the SD logo is similar to the sigma dial that members of the Federation of the Swiss Watch Industry started using from the 1970’s.
Used by makers such as Rolex, Patek, and Vacheron, the sigma symbol was usually printed at the bottom of the dial around the "Swiss" or "Swiss Made" marking proof that the hands and indexes on a watch were made of solid gold. (left is an example from a Patek)
Although used during a different era in watch making history, the Special Dial logo as well as the Swiss sigma dial essentially had the same purpose - to promote when gold parts were used on a watch to enhance the perceived intrinsic value of a traditional watch.
Besides the Special Dial (SD) logo, there were two other logos often found on Seiko watches throughout the 60’s - the AD (Applique Dial) and the ED (Extra Dial). Each represented the different materials used on the index.
[ Special Dial (SD) ] 18k/14k solid gold or 14k white gold for stainless steel cases
[ Applique Dial (AD) ] hard gold plated (referred by Seiko as SGP or strong gold plating) or Rhodium plated for stainless steel cases
[ Extra Dial (ED) ] normal gold plating or nickel plated for stainless steel cases
Seiko watches with the SD logo all had planted index (called 植字 “shokuji” in Japanese). Planted index meant that the hour index (or markers) were set into the dial using pins (often called “ashi” or legs). Setting the index into the dial itself involved
human hands and was an extremely laborious process (just ask the Swiss who used a similar technique but many eventually abandoned the practice).
Above is an example of a King Seiko 1st SD dial. Notice on the back of the dial that there are two holes where the index have been planted. Despite its labor intensive process, “shokuji” planted index was employed by Seiko for an extensive period of time during the vintage era even into the 70's and 80's.
Many AD dials had “shokuji” index but not all were, while none of the ED dial’s were “shokuji” planted and instead the index were all glued.
Above is an example of a ED (Extra dial) Skyliner. Notice how the back of the dial has no holes
In part 2 we will explore the history of the Special Dial
国産腕時計セイコー自動巻 森 年樹
国産腕時計セイコークラウン、クロノス、マーベル 長尾善夫 本田義彦