Originally Posted by percysmith

https://www.americanexpress.com/hk/e...df/HKDA_EN.pdf page 7:

"Fees relating to Settling Foreign Currency Transaction in Hong Kong Dollars

Customers may sometimes be offered the option to settle foreign currency transactions in Hong Kong dollars at the point of sale overseas. Such option is a direct arrangement offered by the overseas merchants and not the card issuer. In such cases, customers are reminded to ask the merchants for the foreign currency exchange rates and the percentage of handling fees to be applied before the transactions are entered into since settling foreign currency transactions in Hong Kong dollars may involve a cost higher than the foreign currency transaction handling fee.

Effective from November 2014"