Socketing

Weapons and armors may come with sockets, which can be imbued with gems. Imbuing a weapon/armor would bring great benefits to your character. Different Gems is empowered with different attributes. For example it can raise your physical attack, magical attack, physical defense, magic defense, accuracy, evasion, hp, etc.. Imbuing can also bring unique glow effects to your weapon/armor. To refine your Gems to a more higher level you can visit the Jewelscraftsman located in every town.

Gems can be bought, combined, dropped from monsters, rewarded from quests or 'Lucky items'.

Each weapon can be equipped with up to 2 sockets and armor can be equipped with 4 sockets maximum. Sockets can be added using socket stones, a cash shop item. Higher level and legendary weapons or armor require more socket stones.

See: JewlCrafting for making higher level gems to place in sockets.