Coins are the currency in Lara Croft: Relic Run. While traversing the ruins Lara can collect coins that she can later spend in the in-game store to purchase new Weapons and Upgrades. There are different kinds of coins with different values: bronze, silver, and gold coins, with gold coins worth the most.
Up until version 1.0.46 of the game, coins could be purchased with real-world money: 1,000 Coins, the smallest amount one could buy, did cost 0,99€. After the update to version 1.0.55 coins can no longer be purchased in the store; tying to buy an item that costs more than you currently posses gives you the option to use Gems to make up the missing amount. Gems in turn can still be purchased with real world money.