I saw alot of Archer use two Lv6 yellow gems on their weapon which is give them around 500 critical attack in total. 
But this sh*t actually give them damage boost from 300 to 2000 on critical hit with auto-attack. 
Just where is these 1500+ came from? 
I guess it’s affected by modifiers.
I’m hitting crits close to x3 normal damage with full str+lv6 yellow gems
Backstab goes to crazy numbers(for such a low base atk skill) with yellow germs
ewww… so contagious. much viral
skill enhance attribute affecting yellow gems too. for example your multishot has 90% attribute then your 470 crit atk from yellow gem changed to 470*1.9=893 crit atk WHEN YOU CRIT. 100% crit required for max dps with yellow gem
Imma Rogue C3, Yellow Gems are a must on main wpn.
i have yellow gems too high crit just went way up. not complaining.