Is it possible NCSoft has made 100% failure rate for compounding jewels to Level 4 due to the fact that it's a reward for the Mammon Staff OE event? I had 40 Gem Energys and tried to get my diamond to Level 4. My LUC is 61 and with Lady Luck buff, it was up to 64. 5 times I was able to get it to Level 3 and all times getting to Level 4 failed.
Very interesting NCSoft...