DBZ Online also have Gems for you to inlay into equipment' sockets. To inlay your gems, you need to find Krillin in the city. He'll be hanging out on right side of the map.
Once you talked to him, you can start inlaying and synthesizing your gems.
Gems are divided to 11 types and each types have 12 Gem Level (Fury gem is an exception, the lowest Fury Gem Level is Lv 4).
Gem types are:
Str : Increase Physical Damage
Agi : Increase Speed
Sta : Increase Health
Spi : Increase Ki Damage
Hit : Increase Hit rate (accuracy)
Dodge : Increase Dodge rate
Crit : Increase Crit rate
Block : Increase Block rate
Piercing : Increase Piercing Damage (can't be reduced by defense)
RES : Increase Chance to Counter
Fury : Increase amount of fury at the start of battle
Each equipment can only have 1 type of gem, so no 2 STR Gem in your armor or weapon. Even if the Gem level is different.
If you have 2 Same Level and Same type gem, you can synth them to get 1 Higher level gem of same type.