Forging system is a feature of the game. A nice gear brings to its owner both powerful attack and defense. If you want to forge your equipment, you need to find the relative NPC in Cronus.
Every equipment has its own level; you can only equip it by reaching the required level. You need a violet stone to level up your equipment. A super violet stone can guarantee a successful up level.
An equipment of the same level has different qualities: normal, refined, unique, elite and super. You need a red stone to improve the quality of your equipment. The name of the forger will be recorded in the gear after a super gear is forged. A super red stone can guarantee a successful upgrade.
Equipment of the same level and same quality still have different bonuses, which will influence the overall properties of the equipment. You need a yellow stone to add bonus on the equipment. If successful, the bonus will add one point, on the contrary, one point will be deducted. (But if your current bonus is 0, 9 or 12, it will not decrease even if the forging fails.) A super yellow stone can guarantee a successful bonus added.
Sockets and gems
There are certain probabilities of making sockets in the equipment when its quality is upgraded successfully. Equipment with sockets can be inserted with gems, which can endow extra bonus to the equipment. During up leveling a equipment, a socket may appear at a extreme low rate. You need 3 red stones to make a socket on a weapon and 10 red stones for the second socket. To make the first and second socket on a non-weapon gear, you need a moon box and a super moon box respectively.