The Shanghai Zuanshi Watch Factory had a long and illustrious history, and made significant contributions to the Chinese watch industry.
In 1958 the factory produced the first pocket-watches bearing the ZuanShi/Diamond brand. Production of stopwatches, primarily for the military, commenced in 1959 . In 1963 the factory produced China’s first 1/100th-second stopwatch; a remarkable achievement and a sign of the rapid technological advances made by the factory.
Another great success for this enterprise was the introduction in 1969 of the SM1A wristwatch, again designated Diamond or ZuanShi. This watch featured a slightly oversized movement with unusually large balance wheel and mainspring. Although a simple design, it was capable of impressive accuracy. In 1972, the SM1A was upgraded from a 18000 bph to a 21600 bph, this movement had been awarded China’s Best Wristwatch 10 times!