1001 Gems?
I just experienced this too. I logged into the game specifically to see how much the new mask cost and what the exchange rate for gold to gems currently is and when I switched back to the gem store tab from the exchange tab it showed that I had 1001 gems. For a moment I thought maybe it was one of those nice quarterly treats Anet does for players who buy gems, so I tried using them but nothing happened. Perhaps it is just a display bug. However, it didn’t open the buy gems interface when I attempted a purchase, which it normally does when you try to buy something with 0 gems – which is the true amount I currently have. So maybe it is more than just a display bug? As far as I can tell it is a random bug because performing the same actions in the same order does not consistently replicate it.