There are three design principles that are fundamental to the Grand Seiko Style. The first one is: “The design is made of flat surfaces and two-dimensional curves, with focus placed firmly on the flat surfaces. As a general rule, no three-dimensional curves should be utilized.” Instead of using curving three-dimensional surfaces, the Grand Seiko Style is composed of extremely sharp and flat surfaces formed from sections of conical ones. The rich “sparkle of quality” comes from the contrasts between light and shadow that these strong surfaces create. The second principle is: “Everything on the case, dial and hands should have as many flat surface areas as possible.” In order to heighten the contrast between the elements and to increase the watch’s legibility, as many surface areas as possible are made flat and the lines on the case, dial and hands are multi-faceted. The third principle is: “All surfaces, as a general rule, should be mirror-polished and be as distortion-free as possible.” This mirror finish further increases the contrast between light and shadow, creating a brilliantly sparkling watch. The mirror finish is achieved by the Zaratsu polishing technique, in which the surfaces are polished until they are distortion-free and by making the edges where the flat surfaces meet the slanted planes stand out distinctively to create a sharp impression. Then, with an inward-slanted case side and bezel wall, beautiful shadows are cast to not only produce expressive sparkles, but also to make the watch look thinner on the wrist. The crown is half recessed into the case to give its side a less obtrusive look and to achieve a comfortable fit for all wrist sizes.

Light, shadow and strong lines. These three elements formed the cornerstone of Grand Seiko Style but, before it could be realized, a new level of precision in manufacturing was required and it came about through a change in the way that measurements were made. Seiko had been using a special unit called “ligne,” which was the mainstream standard in the watchmaking industry but, in 1961, Seiko began to use the millimeter as the base for all measurements. This resulted in a change in the minimum unit from 1/4 ligne (approx. 0.56mm) to 0.1mm, allowing a more precise design of the watch case and exterior components. This change in the dimensional unit standard was particularly helpful in realizing the Grand Seiko Style in which flat surfaces and straight lines are juxtaposed and pinpoint accuracy in manufacturing was needed to achieve it. This change also demanded new levels of skill from the craftsmen and women of Grand Seiko as it was exceptionally challenging to materialize a design with case sides shaped in an elegant arc, as well as indexes and hands with a multi-faceted carved finish. In particular, the Zaratsu polishing technique required high fingertip sensitivity to adjust to the heat, vibrations and reduction in the polishing material while, at the same time, visualizing the final result. It was said at the time that it required at least 10 years to master this technique completely and its use represented a major investment in the skills and number of craftspeople.