Reference article
Coins (Duck Life: Treasure Hunt)
Coins are cave rewards and purchase currency for equipment, pet training and cosmetics.
Earning and spending
Collect cave coins, earn chest and prize-machine rewards, and claim challenge rewards. Coin values can be affected by Gold Purifier and Numismatic.
Currency conversion
Instant Gem costs 75,000 coins for one gem in the supplied shop table.
Across the games
Compare games and editions on the 
Coins page.