Diplomatic Capitol is a new resource introduced in the expansion Rising Tide.
" Diplomatic Capital is the currency of diplomacy. It represents a mixture of your leader's power, experience, and prestige on the global stage. You earn Diplomatic Capital locally from wonders and special buildings, and you earn it internationally when you allow other leaders initiate agreements. Likewise, you spend Diplomatic Capital when you initiate and maintain agreements with other leaders. You can also spend it to level up or change your leader's Personality Traits, which will improve its effects"
- In-game Civlopedia
Diplomatic Capitol, like the Faith resource in the Gods and Kings expansion for Civ:V, is used to gain special perks in the form of Personality Traits and Diplomatic Agreements. Unlike Religious Traits in Civ:V, however, two or more leaders can have the same traits if they wanted to and it is now not a "first come, first serve" style of gameplay. can also be used to buy units and buildings, in the same way Energy can be used. However, the resource cost to purchase is higher for .
Political Traits. There are four types potential Political Traits that offer very important perks. The first one is unique to each faction and the other three are open to all factions. The three other types of Political Traits need to be bought with and all Political traits can be upgraded twice using ; also Political Traits that were already bought can be changed by spending . The cost for each upgrade, new trait, or change in trait starts at 100 and goes up after every purchase. There are 10 Traits for every type of Personality Trait, each with a unique perk and unique potential Diplomatic Agreements that other leaders and can use if they "purchase" them with .
Diplomatic Agreements. Diplmatic Agreements can be initiated and maintained using , and ussualy offer very situational perks. The cost of initiating one can be any where from 25 to more than 250 depending on the power of the agreement. The maintenence cost per turn can be anywhere from 3 to 75 , depending on the power of the agreement.
Purchasing Units and Buildings. When in the purchasing menu for the City Overview, there are two tabs: Purchase with , and Purchase with . The cost of purchaing Units and buildings with is about 50% more than the cost of purchasing the same units with across the board.