Some recent foreign charges from Amex and Capital One. The percentage figure is the idfference from oanda's interbank rate - positive numbers are bad.

Starwood Amex
SGD Singapore dollars 2.18%
IDR Indonesian rupiahs 2.5%
INR Indian rupees 1.89% to 2.3%

Capital One Visa
INR Indian rupees -0.18%

It has always seemed to me that the Amex rate diference tends to be higher in countries which have more volatile exchange rate.

Nice to see that Capital One is actually slightly better than the interbank rate. I think it is clear that they do not pass on the 1% Visa charge.