Just a note to let you know I’m merging about half a dozen posts to gather all the reports of players having trouble buying gems in the Gem Store. This means you may see some repeated comments within the thread, but making a merged thread allows us to give you one single, update so you know the status of this issue and it will make this issue and its upcoming resolution more visible.
In a nutshell, and I’ll post this at the bottom of the thread as well, we’ve been able to determine that our billing system provider has had an issue that has prevented some players from making a Gem Store purchase. Quite honestly, it was pretty hard to find what was going on, which is why for a few days we were not able to confirm exactly what was causing the issue, and we did wonder if the problems were unique to individual players. At this time, the provider is actively working on a fix and we hope to have this all ironed out very soon. I’d suggest that you do not need to submit a ticket, but you may if you wish to do so.
I will update you as soon as I have more information. In the meantime, please accept our apologies and our sincere thanks for your (attempted) support of our game through Gem Store. We hope you’ll make that purchase as soon as the problem is worked out. 
Thanks!

) but it’s best to avoid the hassle for you by simply clicking once and then waiting a bit to see if the purchase goes through.