Purify Gems

Purify Gems can be found in stages. They are on, and surrounded by, Absolute Polluted Land which can not be purified by normal means. To purify the land and unlock the Purify Gem, you must first purify one of the adjacent tiles by means of merging. Once done, the land the Purify Gem is on will also be purified and the gem will become accessible. Then, you can tap the gem, or simply wait, and the rest of the adjacent tiles will be purified.

The Purify Gem and adjacent tiles on Absolute Polluted Land

After merging with an adjacent tile, the Purify Gem is purified

After activating the Purify Gem the adjacent tiles are also purified