This game are played by players from different country. Payment method is limited in some country.
So, how about to create SG his own market/online shop to sell packs of gems with different method to everyone? Using e-wallets, Credit Cards, Pre paid Cards, etc.
People who made payment on this marked, should receive on his email a code or key to put on his Empires & Puzzle account to redeem gems. Also can be used this method to make gift to another player.