From Anet:
As many of you are aware, there are some exciting changes on the horizon! The Black Lion Trading Company is making some adjustments, which I’d like to address now:
To support the new Wardrobe system, Transmutation Crystals and Transmutation Stones will be converted into Transmutation Charges! Double-click on stored Crystals to convert them 1:1 into Charges, and double-click on stored Stones to convert them 3:1 into Charges. Transmutation Charges will replace Crystals as drops from the Black Lion Chest.
Transmutation Splitters will continue to work on items that were transmuted before the April 2014 Feature Pack. You also have the option of exchanging Transmutation Splitters for 5 Charges at a Black Lion Armor Trader in any major trading post.
From April 15 onward, your Trading Post history will show only the last 90 days.
To get you started with this new system, we’re giving away five free Transmutation Charges per account to everyone who logs in between the launch of the Feature Pack and 11:59 p.m. PT Wednesday, April 16! Visit the Promotions tab in the Gem Store to check out this and other offers!