Where does the name 'Shirakaba' of Grand Seiko's Heritage Collection SLGH005 come from? "Shirakaba" in Japanese means birch, a tree that surrounds the brand's headquarters in Shizukuishi. In fact, the dial is reminiscent of a birch forest with endless silvery trunks, thanks to the irregular vertical pattern decoration on a satin-finished surface. The hour markers and hands are free of luminescent substance and are therefore invisible in the dark, but in the presence of even the faintest light source, the mirror polishing of all their facetted surfaces and the satin-finished insert in the hour hand ensure excellent legibility. The steel case recalls the design of the first Grand Seiko models from the 1960s.
The setting is that of an elegant sportsman with a weight of 176 grams and a three-link bracelet with polished edges. The contrast between the brushed and mirror finish creates a refined aesthetic impact. Polishing is one of the points of pride for the Japanese craftsmen, who have been developing a technique since the 1950s: Zaratsu, still practised with vintage machines, consists of using the entire surface of the rotating disc, instead of just the edge, and makes it possible to obtain a much more homogeneous and long-lasting result to which an extra-hard scratch-resistant coating is often added to extend its life.
At its heart is the innovative automatic calibre 9SA5 with 36,600 vibrations per hour (Hi-Beat), 80 hours of power reserve, resistant to magnetic fields up to 4,800 A/m, and set to a stated tolerance of -3/+5 seconds per day. The reduced thickness of 5.18 mm, thanks to the redesigned gear train, makes it versatile and certainly adaptable to many other references in the future. It adopts the Dual Impulse escapement, which reduces friction while optimising energy consumption, and a free-sprung inertial regulating balance. After three limited edition models, the Shirakaba is the first to be equipped with the 9SA5 calibre.
