Day Crystal

The Day Crystal is a Accessory that gives extra  and  during the day. It is unlocked at Its other counterpart is the Night Crystal, which gives you extra  and  during the night.

In total, it takes 26,240 quartz to craft, which costs around from the Bazaar. You might be able to find it for about 110k coins on the the Auction House because some people just want to get it sold.

Crafting
Quartz can be found in the Blazing Fortress but it is recommended to use a Quartz Minion, because a lot of new players are farming Quartz for Mining EXP or EXP. In general, mining manually is really inefficient.

Trivia

 * The Day Crystal and the Night Crystal were used to be able to be put together in a Crafting Table to make a now (technically) blacklisted accessory known as the Eternal Crystal.