It's important to take this information with a grain of salt since the market is still adapting to the recent changes, and all realms will experience the changes differently.
With the release of Tier V raw gems to the market in exchange for heroic badges, there has been what seems to be about a 60% cut in gem prices.. red gems have dropped easily 80%. No single red cut is competing at a price higher than 30g, and at the moment even that looks like it will slip from competition soon. Most Forest Emerald cuts have been flooded below the profit threshold. Raw gems are predictably selling for even less.
I expect things to stable out with prices on most cuts dropping below the profit threshold soon. Hopefully, from there, the market will recover after all the badge hoarders have spent them all and aren't flooding it. I certainly don't anticipate a full recovery, but judging by the recent pre-patch state of the Frozen Orb market I'm hoping for at least a 30-40% recovery across the board.
Any one else's realms taking a hard hit that it looks like you'll just have to weather through for a while?