Hello Juji,
I see you try to fix this problem with greedy chests. But removing the system is not a fix, this is deleting a content. Try revamp this, as many ppl already said - chest appear only when mob is killed. Also check other regions . How they fixed this, why there is no problem there...? I can tell you why, they just flood the server with these jewels, so everyone can buy it...
For example ruby 5 in CORE was like 25b !!!
Also give us opportunity to buy what jewel we want from Night Market shop. As all other regions did, not this random crap!
Just my opinion.