Depends on how they want it to work, you could refine with confidence on official as with a good recipe you could get to quite a high/consistent % chance of it working (not to mention jumps of +2 or +3 these exist here?), refined level 40weps to +6 and did a 14 stat refine on a level 36 wep so the possibility was there. If the code is anything like say crafting gems then you will never confidently refine anything short of lowish level practically shop items (cap of 70% with a perfect recipe-> maybe 50% with an average recipe? maybe alot less?) this is just speculation at this point, I have not talked to anyone that has any confidence refining yet. But might take some time, depending on the complexity of the system (variables could include the wep your using, body luck(we know it does) amount of jewlery used, amount of different type of jewlery, level of jewlery, base stat of jewlery, top stat of jewlery, combined total stats of the max or min or both of all jewlery or just some, stats of the worst piece of jewlery used, or the best, or the highest amount,etc etc)