From Guild Wars 2 Wiki
Knowledge Crystals are a currency earned by completing the Crucible of Eternity dungeon in explorable mode. They are stored in the Account Wallet and can be traded to the Dungeon Armor and Weapons merchant at Vigil Centerhouse in Lion's Arch.
- 20 Knowledge Crystals are given for a completion of each chosen Crucible of Eternity explorable path, with a bonus 80 for each path once a day.
- 3 Knowledge Crystals are obtained from each Bag of Wondrous Goods dropped by an Crucible of Eternity explorable mode boss.
- 60 Knowledge Crystals are obtained from each Crucible of Eternity Token Loot Box, one of the rewards for progressing in the Crucible of Eternity Dungeon Track in PvP or WvW.
- 150 Knowledge Crystals can be chosen from Chest of Dungeoneering.
- 300 Knowledge Crystals can be chosen from Tyrian Exchange Voucher.