To extract Mana from Mana Stones you need to visit the Jeweller.
Mana: Mana can be acquired in 3 ways. You earn Mana from Daily Logins, Daily Quests and by extracting it from Mana Stones.
To extract Mana, you first need have one of the Mana Stones which you can find in your adventures from opening crystal chests. Once you have any of the Stones you can bring it to the Jeweller.
When you visit the Jeweller you will get a menu like this. Just drag the Stone into the center and hit Extract.
1: The Jeweller will gain XP from Extracting Mana Stones and you will be able to store more Mana depending on your Jeweller’s level.
Once the Mana Stone is placed, it will tell you how much it costs to Extract, how long it will take and how much Mana you will receive. Just hit Extract and it will start Extracting.