Found a small exploit on my mage tonight. If you summon a mana gem and then use the glyph Mana Gem (When you summon your mana gem it has 10 charges on it instead of 3) on your mage and summon a Brilliant Mana Gem you will have both.
It's not a huge exploit but only costs a couple silver and saves some time and gives you 13 uses of mana gem before you have to summon another.