Beijing 北京 Shuangling 双菱 (Double Rhomb) 20J

Model : Shuang Ling 双菱
Manufacturer :Beijing Watch Factory 北京手表厂
Year of Production: 1970s
Case Diameter : 
Weight w/o strap: g 
Movement Model : ZB-1 (20 jewels) 
Type : Hand Wind 

Shuang Ling 双菱 was also branded as Double Rhomb by Beijing Watch Factory. Literally, shuang ling means pair of rhombuses which is depicted by the logo itself. A pair of rhombuses stacked together at the corner is a traditional symbol of beauty, all minds as one and good luck. The symbol is known as fang sheng 方胜.

The movement is ZB-1, a 21,600bph movement with 20 jewels.  There is no for this ZB-1 I can't ascertain the date it was made save only to say that it  was a 1970s piece. A  relevant quote from the wiki:
"Beijing Watch Factory was one of the enterprises at the forefront of the Chinese Standard watch project. Beijing's version was the 20 jewel ZB-1, which entered production in 1974. The new brand name, 'Shuangling' was chosen as part of a shift towards an export focus for the factory. On foreign markets, Shuangling was translated as 'Double Rhomb'. These were sold in various parts of East Asia, and some were exported to Britain in 1978-79.
In the early 1980s the ZB-2, a thinner 17 jewel Standard movement, was developed. It entered production with the Standard code ZBJ, while the older ZB-1 was transferred to the Beijing Number 2 Watch Factory as the ZBE. " (see link here)
The caseback design is simple which is only engraved with the logo, "China" and "ZB-1" bordered with a flower, simpler than I would expect for a 1970s watch.

For those who craves for photos, they are here:

The Portrait
The Movement 1
The Movement 2
The Movement and the Caseback

My other watches from Beijing Watch Factory are here:
Beijing 北京 SZB-1
Beijing 北京 SB-5