Cal. 8L88 was the fastest Hi-Beat movement ever produced by Seiko and set the stage for the modern 9S8x Hi-Beat movement family. Although it was only ever seen in a single watch model, the limited-production Credor GBBX998, and is not widely known, it was a critical development for Seiko in the 2000s. By producing a 12 Hz (43,200 A/h) movement, the company showed the quality of its engineering and metallurgy capabilities. Twoyears after the 2008 introduction of the Credor 8L88, Grand Seiko returned to Hi-Beat movements with the 10 Hz (36,000 A/h) Cal. 9S85.
Note that some sources list the date of introduction for the Credor Juri Tenga with Cal. 8L88 as 2006, but Shizukuishi Watch Studio officially lists the introduction as 2008.
The GBBX998 was an exclusive watch with a rectangular case constructed of 18k gold and rare Japanese lacquered wood. The “Super Hi-Beat” balance was visible through the open heart dial at 10:00. On the rear, a transparent case back showed the central winding rotor and balance. A power reserve indicator pointer was positioned at 3:00.
The watch retailed for 50 million Yen (about US$600,000), making it the most expensive Seiko watch ever produced, though the dial simply said “Credor”. The back was quite wordy, however, with “Water Resistant”, “Made in Japan – Seiko”, “8L88-00A0 – 18KT” and the production number “8 10001” listed around the aperture. The rotor was inscribed “Super Hi-Beat” and the movement shows “Seiko Time Corp/Forty One Jewels/8L88A/Credor.”