We mages can create mana gems. Our first gem is craftable at level 28, and it restores 375-425 mana. Our latest gem is craftable at level 68, and it restores 1136-1364 mana. And there are several gems in between.
The catch is, we can only carry one gem of each type at any given time. In other words, we can't conjure up 5 of our best gem. Many of us have resorted to conjuring our highest ranked gem and our next-highest. We do this so we can use two gems in a single boss fight, if necessary.
It's almost pointless to create a third or fourth down-ranked gem though, because the amount of mana restored decreases with each lower rank.
The latest gem improvement, announced here, will change all that. The improvement is two-fold:
1. The highest ranked gem will restore 1800-3000 mana (the same as the highest mana potion, [Super Mana Potion]).
2. The gem will have 3 charges, so we can use it three times before having to create a new one.
What does all this mean? First, it means that you won't need to buy as many mana potions. You'll only need to burn a potion when you've first burned through all 3 of the ones you can conjure.
Secondly, it means that you won't need to conjure up lower-ranked gems in order to have multiple gems on hand at once. Essentially, we will be able to carry three of the highest ranked mana gems at once.
Thanks Blizzard. :-)