Among the currencies circulated in the republics, the most popular are the Ducat Gold Coins minted by the central minting house of Sea Blue.
[Note: The term "Ducat" originally meant "money coined by the Duke," used by many regimes to refer to their own issued currency. However, with the popularity of the Venetian Ducats, the term now specifically refers to Venetian Gold Coins.]
The Venetian Ducats were almost pure gold, with a stable quality, so their value was the most robust. Large volume transactions were all priced in Ducats, making gold coins minted by other Alliance nations seem inferior by comparison.
For example, consider the gold coin with a larger circulation volume—the Gold Coin of The Federated Provinces, usually ten of these coins were only worth seven Ducats, and if used for payment, compensation for the seller's melting loss had to be provided.