Shanghai 上海 Zuanshi 钻石 (Diamond)

Model : Zuanshi (钻石, Diamond)
Manufacturer : Shanghai Stopwatch Factory (上海秒表厂)
Year of Production: 
Case Diameter : 
Weight w/o strap: g 
Movement Model : SM1AK (17 jewels) 
Type : Hand Wind 

This is Diamond from Shanghai Stopwatch Factory. You may see wiki here for more information about the factory and a fine chronology about the factory here. The movement is SM1AK with a beat rate of 21600bph and cited below is from the wiki  
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, in line with industry trends, the SM1A was upgraded from a 18000bph to a 21600bph escapement. By the time production ceased in 1983, the SM1A had been awarded China's Best Wristwatch 10 times!
"K" the suffix of SM1AK is the first letter in pinyin "Kuai" (快) which means fast or quick; so K could represent "fast beat"; this is just my best guess. 

The caseback is engraved with the diamond logo at the centered and surrounded with the words 上海秒表厂 (Shanghai Stopwatch Factory), 防震 (anti shock),全钢 (all stainless steel), SM1A-K and 106. The 106 should be the model/watch design number.

Found a thread in Watchuseek forum which has some rare and interesting Zuanshi; this is the link.

Also found is an once-upon-a-time popular Chinese song in Taiwan named "钻石亮晶晶“ meaning "the sparkling diamond" in 1969; it is not about this watch  but vintage enough to be together on this page.  Warning: please do not click on the  following link if you cannot withstand the music of late 1960s or early 1970s. The link is here.