I'm seeing a very similar situation on my server (****, it might be the same server) - cut inferno rubies had been holding steady at about 100g, now down below 70g. Also raw amberjewels and sapphires hovering near vendor price, cuts in the low teens if they sell at all. Hessonite barely above the 9g (cut) vendor price, zephyrite at it, and alicite under (as low as 6g!).
I blame either a farming consortium, or more likely a bot wave, that drove both Elementium and Obsidium down to - and often below - the prospecting "vendor" price (i.e. the expected value of just cutting and vendoring everything you prospect - 54g for Obsidium, 36g for Elementium).
For now, I've given up transmuting, even carnelians. I'm stokpiling most rares in hopes of a recovery either through 4.1 or rising ore prices. Elementium is almost certainly better for creating bars rather than melting into gems. Crafted jewelry still is selling, but the rare gems (and half stack of Elementium) were never a major component, and it's not exactly high-volume.