If the AI has gpt to offer you, and you haven't done anything to sully your reputation, you can give trade a lump sum of gold for their gpt at the rate of 18 gold/1 gpt. That is, if you give them 18 gold, they can give you 1 gold per turn. If you give them 36 gold, and they have 2 gpt, they can give you 2 gpt for that. It also works the other way around in that you can buy 18 gold from them for 1 gpt. I have a game going right now, where I feel confident I haven't sullied my reputation, and I can't get these trading rates, and I believe that the ratio of gold/gpt for 1 gpt isn't the same as for 26 gpt. The AIs have signed some trade embargos against me. Can trade embargos mess up the trading rate?