I have all goods required for the next Advancement, but the game still asks me to pay Diamonds!
In addition to the goods, your Settlement also requires you to have a certain level of diplomacy to unlock an advancement. Diplomacy is generated by Diplomacy-Buildings, such as the Runestone. If you do not have the diplomacy required, you can use Diamonds to ignore the requirement and unlock it right away. Otherwise, please build more Diplomacy buildings.