You may want to look into it. The fail rate should go up with the lvl, not be 75% ( three of the four failed, I have experience for 8 ) unless this is how you want rings to work. But really that would take years of grinding to get them lvl'd. Please look in to it. I don't care about the loss of hard to find stones, more as people new to pso.
I know rings fail, but there is something weird going on with the odds through out the game. I am not hating on the game. I love this game, I just letting them know it may be a problem.