Rates - some of them can be observed:
ICBC old dual currency (Visa/Unionpay):0.8544
http://www.icbcasia.com/b ... rmbexrate.shtml
ICBC Guangshen dual currency (Unionpay only):0.8534
http://www.icbcasia.com/b ... rmbexrate.shtml
BoCHK:1/1.1736889 (this is the rate quoted by my BoC ITS banking right now)=0.8520