If some of you do not know , there are several ways to take these gems;

Area 1 (around arena) 2 chest spawn every 30 mins(make sure ur using Amp of luck, or u will get just 1 gem)
Kiji 2 (Shaitan, 827,3499) 3 chest spawning every 1h
Bounty hunter (Winter island 245,878) You gonna win to get Chests, also u get kylin cards and acc bags
Chaos argent (Icicle) same as bounty hunter
Battle royal which is in shaitan's city , near teleport
and thundra map, also here u can farm 10m notes,good for new players.