I have attempted to buy gems on multiple occasions. Only once have I been successful, every other time, my CC declines the charge and I get a phone call in the morning asking about potential fraudulent activity that has been occurring on my account. I tell them that the charge is okay and to go ahead and accept it, however of course, I receive no gems, and the next time I try to make a purchase, it gets declined again. This has happened probably about 6 times.
One time I was able to successfully make a purchase, but 6 other times, my CC has declined the charge for potential fraud, and at 8:00AM the next morning, I get a phone call from my CC to verify the charge. It never fails.