Fix the broken boat
Fix the broken boat that lies on the shore near your village. No special tricks are required to do that. When you update the game to the latest version, you will be able to fix it normally.
Travel to the new village
The boat will allow you to travel to the master builder’s remote village where the gem mine lies. Just click on the boat to travel there.
Upgrade your builder hall to level 3
Before you can fix the gem mine, you will need to upgrade your builder hall to level 3.
Collect 120,000 Elixir
Collect 120,000 Elixir in the new village by attacking other villages. This amount is needed to fix the broken gem mine, which is located on that island.
Locate the broken gem mine
The gem mine is located in the new village in the north west. You might need to clear some trees in order to recognize it. (See How to get free gems in clash of clans?)
Rebuild the gem mine
Rebuild the gem mine and it will start producing 2.1 gems per day. Upgrades can push it to produce more, but you will need more elixir.
Upgrade the gem mine
You can upgrade the gem mine 4 times until you reach a maximum production capacity of 3.1 gems per day. You will need a big amount of Elixir in order to do so. (See How to Protect Resources in Clash of Clans?)
How to find and repair the gem mine in Clash of Clans?
How long does it take to rebuild the gem mine in Clash of Clans? How to find and repair the gem mine?