When it comes to rare and unusual vintage Grand Seiko models, the Ref. 5646-5010 undoubtedly stands out. Featured exclusively in the 1973 catalog, the Ref. 5646-5010 likely wasn't among the most successful lines of vintage Grand Seikos. This limited production period helps explain why it has become such a rare reference to come across today.
 
The dial features a gradient of yellow, white, and brown, known as the "Kira-Zuri" texture. This distinctive and mesmerizing finish is unique to this reference and has also been showcased in recent Grand Seiko models, such as the US 2018 Limited Edition Grand Seiko (SBGA387, SBGA385, and SBGA384).
 
The Ref.5646-5010 stands out with its unique square case, distinct from the rest of the vintage Grand Seiko collection as it diverges from the Grammar of Design (G.O.D.) principles. While its unconventional design might seem surprising at first, the intricate details will soon captivate you. The contrast between the brushed and polished sides of the C-shaped case, particularly on the edges of the lugs, is stunning especially when it plays in the light.
 
This 56GS model is truly sublime, retaining its original look with the correct GS buckle, black Seiko alligator straps identical to the originals, and the original box. And with this set, we hope it offers an authentic unboxing experience reminiscent of when it was first sold.
 
Shipped from Tokyo, Japan