Originally Posted by
azthal
The gem store (whatever it's called now) is not an auction house. It's more like a supermarket.
The market buys gems from producers at a set price, then re-sells it to the consumer.
If there's a high demand, but not much avaibility, the price goes up. If it's high supply and low demand, it goes down. The difference would be that the supermarket in this case doesn't take a cut.
ANet have said they looked allot at Eve making this, and I would assume the reason they went with this road instead of just allowing gems to be sold on the normal auction house is because of the extreme price differences you found for PLEX in Eve. To make a good deal, you sometimes had to wait days to trade your plex for ingame money.
By having a centralized market instead of an open market, you won't have as much difference in the costs. The costs are flattened out, giving a more even and stable cost.