The Japanese electronics company, Toshiba, started a long running relationship with Grand Seiko in 1965.
Toshiba commissioned Grand Seiko to produce watches with custom casebacks to present to employees completing 25 years of service with the company.
Over the course of nine years, four different references were used as the base watch for the commemorative piece, starting with the 5722-9990.
For all the references, only the caseback differs from the base watch, with the commemorative year shown above the medallion, and the inscription arranged around it.
Interestingly, with the inscription taking pride of place on the caseback, there was no space to stamp the model number, nor the caseback serial number. These references can only be seen on the inside of the caseback when it has been removed from the watch.
For the watches based on the 57GS series, Grand Seiko actually used a different reference number to that of the base watch – 5722-9970.
The 5722-9970 was used for the first four years of commemorative watches, with 1965 and 1966 being based on the 5722-9990, and 1967 and 1968 being based on the 5722-9991. Despite the change in base model, the reference number found stamped on the inside caseback for the 57GS Toshiba Commemorative watches remained the same.
(note – we have not had the opportunity to photograph any of the 57GS watches – the banner photo for this article shows the caseback of 1969’s 4522-8000)