In short, two types of stones you can use to increase equipments' abilities.
- The first one is Upgrading gem (or illusion stone), which Enforcer already told about. You can use this type of stone for ugrading equipments to next level +1, +2, +3... Each level has bigger effects than previous level. Equipments have difference effect depends on theirs types:
+ Weapon: Upgrade physical weapon ---> + physical atk (dmg). Upgrade Magic weapon --> + magic atk (dmg).
+ Armor, boot, helmet, wrist, loin-cloth, knee, cloak: + HP
+ ring: phy. ring --> + defense; mg. ring --> + mg resist.
+ necklace, amulet: depends on types: + HP, + MP, +eva...
There are 12 level of upgrading (arcoding to wei xiabao. Don't worry, he don't lie about this prob ^^). Each level has bigger effect than previous level does.
Level/Effect: 1/1, 2/2, 3/3.05, 4/4.3, 5/5.75, 6/7.55, 7/9.95, 8/13, 9/17.5, 10/22.03, 11/29, 12/37.5. For example: if upgrade level +1 has effect +24 defense then level +12 will add 24*37.5 =900 (^^) to defense.
Cautions: If you upgrade successfully, equip will up to next level. If not, equip will be dropped level(s) (at high level, it may drop more than 1 level each time).
When upgrading, you can use some special stones:
+ Earth Stone

: increase chance of success and decrease possibility of dropping level. If equipment is dropped level, it will be dropped 1 level.
+ Heaven Stone

: has bigger chance of success than Earth Stone, but doesn't have anything to do with possibility of dropping level.
+ Dragon Stone

: chance of success is 100%. But each type of Dragon Stone only has effect on certain levels of equipment. Example: 1st-level Dragon Stone will give 100% chance of success in upgrading equips to level +1, 2nd-level Dragon Stone will give 100% chance of success in upgrading equips to level +1 or from +1 to +2,......(see picture: there are 10 types of DS from level 1 to level 10).
- The second type of stone is soul stone (as every one said before). If equipments have soket(s), you can use those stones to fill soket(s) and have additional effects. Those stones also has different levels. Each level has bigger effect than previous level does. Your equipments can emit light if they have at least 2 sokets filled with level-5 soul stones or higher level soul stones. (But if your weapons is 3* then they can emit violet light no matter how many sokets they have).