Diamantes
Diamonds are the "premium" currency of the game that can be bought with real money and can be spent on almost all aspects of the game. For example players can buy premium buildings, forge points, expansions, missing blueprints, goods etc.
Players can receive diamonds in game through some quests, buildings, Guild Expeditions rewards and conquering certain provinces, however those occurrences are fairly rare.
In the 2013 Summer Event there were a chance of winning diamonds at the wheel of fortune. In the 2013, 2014, 2015 and 2016 Winter Events had a Diamonds 250 diamond package as a daily price in a single day of the event.
Diamonds are shared between all worlds on your same account. If a player that has a city in two or more different worlds earns diamonds in one of them then those diamonds can be spent on the other worlds. This has led some players to build additional cities that focus on building Wishing Wells to get diamonds (the only reason why they have these cities is to get diamonds). Those cities are sometime referred to as diamond farms. The purpose is to use those diamonds to benefit the main city of the player. Diamonds are not shared between different regions but only worlds that are in the same region (e.g. DE, US, EN,...).