That isn't true. A gold exploit caused this inflation. This has been confirmed on the Polish Boards where I beleive their problem is even worse than yours is here, and that is with the Dia NPC enabled.
It was calculated (I have no idea how accurately) that from one Polish ebay-type site - 3kkk illegal gold was sold every day for one server. The inflationary of effects rich endgamers hoarding gold, or the price of a puri (when many t6 their armour or above) when compared to this is absolutely neglible.
The gold exploit is closed, and the idea that the hard limit of how much gold you can have on one account will be worth nothing is just not true.
Just as lots of people are doing very well out of this inflation, many are doing very poorly, but it will stabilise eventually. And hopefully players will help out with this, cause I think that if the developers have to get involved to take direct action in the economy people are not going to be happy about. I reckon that would be absolutely brutal.
You and aardvark are both right actually. Gold value was artifically high because a lot of really rich end-gamers were holding onto their gold, not doing anything with it. When the new chapter came out, those same end gamers started regearing, and rather than buy diamonds they sought to buy diamonds from other players. Diamond seller supplies were low, demand was on the rise, so the price of diamonds skyrocketed. More of the end-gamer gold reserves were released into the economy, driving down the relative value of gold. Didn't help that players equated, at least to some degree, the value of their equipment with the value in diamonds it cost to make the equipment.
Gold supply increased, diamond price increased, gold value decreased. Prices go up, unscrupulous players turn to gold sellers to help fill the void (gold seller gold is either dupped, or it is also sitting in large stockpiles waiting to be released into the economy), and the cycle continues.
Luckily, overly high demand for diamonds wanes after end gamers get their gear all supped up; gold sellers are being dispatched at a healthy rate; illegal gold is leaving the game; and end-gamers can start selling gear/stats on the AH, which will drive the AH prices back down again. Give it time, and with a little help from Frogster (economy update this week Swag? You promised........) and things should get back to normal.