Well you have certainly found a sure fire method to utilize this event, i'm sure IGG will appreciate your sharing this exploit on their forum.
Follow IGG @Facebook.com/IGG Follow CC @Facebook.com/CastleClash
A good way to get Gems, although I prefer to use my smurfs acc to lvl up my guild and sentinels.
If they don't change the Gems like reward, maybe they could limit one invite per account. Pray IGG don't check this post.
Facebook IGG: https://www.facebook.com/igg/?fref=ts
Twitter CC: https://twitter.com/CastleClashIGG?lang=es
Twitter IGG: https://twitter.com/officialigg?lang=es
Instagram CC: https://www.instagram.com/castleclashes/
Instagram IGG: https://www.instagram.com/iggigotgames/