According to the old forum posts, the closer your equipment is to the jewel's max level, the higher the fail rate. If this is true, then we'll be seeing more fails with the level 77 equipment compared to lv 70 equipment.
It's been my experience that fails or fails+level drops are built into "standard" (non-perfect) enhancement gems, based on a certain percentage chance, and also based on some sort of random number generator (RNG). Since I'm not a programmer at all, or CS student, perhaps someone with experience ('wiffo?) can explain in one-syllable words how RNGs don't actually produce truly random numbers.
Now that I've said that, I've had rather variable success when plussing gear that's close to the upper level limit for given "standard" plussing gems. My mileage varies, and yours will, too.
So far, it still seems to hold true. Had no problem getting to +5 with Faith jewels on old 70/72 equipment. But with level 77 pieces, even +4 is hard. And from what I remember before faith jewels came out, it was almost impossible to get +5 with revelation jewels on lv 67 or 70 pieces. +4 was recommended, and 2 perfects after that. When Faith came out, +5 became possible easily. Now we're probably just going back thru the cycle again, and with perfects being so expensive... yeah, this going to be a problem.
There have been times when I've had similar gear go from +1 to +5 in five or six tries. And then, there have been times when it's taken 10-15 tries to hit +5. Going from +12 to +15 usually goes smoothly for me, with few fails or fail/drops.
But when I run into a stretch of fails and fail/drops, it's time to put down the plussing gems and walk away for awhile, maybe even a full day. Change of time, change of luck, perhaps.
I think that it's not only unconscionable but also a waste of time and text to repeatedly bring up this subject. I've lost count of the number of threads that have been started and maintained about it over the years. No matter how often this stuff gets yammered about, neither the publisher nor the game developer seems to be willing to make a change to the fail and fail/drop chances. *That* much is obvious. After all, selling diamonds so people will buy Item Shop stuff is what keeps this game going.
I will admit that I'm puzzled, and occasionally entertained, by the people who insist upon coming back to this, as a dog returns to his own spew. But good Bog, it can't be *that* tasty...
It's also ridiculous to make a claim, as the OP did, that GF or RW "raised the price" of plussing gems. I seriously doubt they've done any such thing. What I believe is that the OP had one or more runs of poor luck, that the RNG gods were mad at him for not having made a sufficient sacrifice, or that he simply wasn't holding his mouth right when clicking on those gems.