there are nomral, superior, rare and legendary earings.
The max stats in the reare is 28. You can obtain rare earings from muddosa gamble, action house or any bid.
The max stats in the legendaty is 34. You can only obtain legendary jewelery in the bids and they are not tradeable. So you can only obtain playing the bids.
Once you get your jewelery you need to box it and get the stat you need.
To get brown boxs you can donate to the server and try your luck with the gamble machine. Buy it in AH or any trading post. (the actual prices is betwen 50 - 65kk, dont let you scamm from those who are selling box 70++kk)Or you can do the event boss a lot of times. (The one with the magins). The merchant of this event will sell you one brown box for -4 golden coins +10kk. (Or two or any amount you want meanwile you have the coins and the zeni)
Gl