Hey, this is a little trick i came across when i got a meta gem open.
If for example you were trying to get Chaotic skyfire diamond which requires at least 2 blue gems:
1) Equip gear that has the gems you require for meta gem.
2) Put in your Meta-gem.
3) Unequip gear and put on what you originally had.
4) The meta-gem stays active and you dont need the gem requirement since the meta gem is already in!