If it fails you get a Blessing Point, the higher your Blessing Point the higher the chance that it will succeed (hover over blessing points ingame). As each Refinement level Requires more and more Blessing Points to fill up the bar, the chance to gain instantly a rank decreases making higher level Refinements harder to reach.

My theory you would need only 10 blessing points left to reach the same chance as level 1 refinements.
This post was last edited by Trickz at 2016-8-18 01:36