Upon your guild reaching level 8 the Mill will be unlocked.
The best way to get Guild Coin, is by using orders. The number of orders available depends on level of the guild mill. Orders can be upgraded to give more rewards, up to a maximum of 6 stars. Upgrading an order costs Gems. You can get new orders every 12 hours, regardless if you already completed the available orders (the new orders will be added to already started orders but replace orders that are not started yet).
|Stars||Time||Base reward||Upgrade cost to next star|
|1||10hrs||150K , 65x||10x|
|2||10hrs||180K , 70x||20x|
|3||11hrs||220K , 80x||30x|
|4||11hrs||260K , 100x||60x|
|5||12hrs||300K , 130x||100x|
|6||12hrs||350K , 180x||-|
You and your guild mates will donate Gold to upgrade the Mill giving you more Gold and Guild Coins per Order. As of Patch Android 1.11.7 / iOS 1.9.9 the maximum level of the Mill is increased from 6 to 10.
|Level||Upgrade cost||Order Yield||# of orders|