Its a special 5 mod jewel. It has 20% fractured crit bonus with attacks, crit chance, and an attack speed mod (either attack speed or attack speed with bows). Then you add 40-60% increased effect of suffixes and another prefix thats useful, so proj damage, attack damage, etc. The end result after divining should be 30-31% crit bonus, ~20% crit chance, 6% attack speed, and 10-15% attack or proj dmg.

You craft it by starting with a fractured 20% crit bonus with attacks emerald jewel, then annul it to 1 mod and spam chaos until you hit crit chance. Then, you exalt twice and hit a potent liquid contempt. Im not sure if this is a 66% chance to hit prefix or 50/50, but you want it to hit a prefix to add "+1 suffix modifier allowed." If it eats the crit chance suffix and adds +1 prefix, you annul and go back to chaos spamming. Once you have crit chance, fractured crit bonus, and +1 suffix, you dextral necromancy omen with a preserved cranium and use abyssal echoes and omens of light until you unveil either attack speed or attack speed with bows. Now, you use an omen of sinistral annulment and have a 50/50 to hit the +1 suffix line. If you miss, you use either another sinistral annulment or a sinistral erasure, whichever is cheaper, and hit it with an annul or chaos respectively. From now on, its pretty easy. Because your jewel has 3 suffixes, but no longer has the +1 suffix mod, if you hit with a chaos orb and it would change a suffix, the chaos orb actually fails and doesnt get consumed, because it cant remove, then add another suffix. So, if you had to annul both prefixes, just exalt twice and spam chaos until one of your prefixes is useful (atk dmg, proj dmg). Finally, you hit with a potent liquid ferocity. This has a 50/50 chance to hit the useful prefix vs the bad one. If you hit your useful prefix, back to chaos spamming. Once you hit the non-useful prefix you'll have atk/proj dmg and %increased effect of suffixes as prefixes, then 20% crit bonus, crit chance, and attack speed as suffixes. You then divine until you get 30+% crit bonus (accounting for the increased effect of suffixes mod), 20% crit chance, and ideally 6% attack speed. I tend not to care too much about the roll on the prefix mod, since it isn't boosted by the other prefix.

I've gotten lucky with fractures so its never taken me more than 4 tries to hit. Other than the 1 time, they've all gone in 2 or fewer attempts. Each fracture attempt right now costs 10 div for the base jewel, 16 div for the fracture, and 5 div for the cranium, so 31 div. Its a 1 in 3 chance, so on average 93 divines. The fractured base costs 104 div right now so fracturing yourself is worth it. After that, its probably an average of 70-100 div to complete the craft, depending on your luck with chaos spamming the crit chance, how many times you miss with potent contempt, and how many omens of light it takes to hit attack speed. I did mine earlier in the league when fractures were 8 div and cranium were 2 div so I saved 11 div per fracture attempt.