Apparently, Kabam can be really messy with their communication (who knew, right?). Remember the mail which stated what the Gems would all buff? Here it is:

Seems as if Kabam is confused on what attack and life debuff means, beause as most of you have found out, the Sapphire and Citrine Gems are reversed in effect: Citrine debuffs enemy life, while Sapphires debuff enemy attack. Anyways,  I changed it in the Gem Embedding article to reflect the correct buffs and levels now….