guide
MU Online jewels
Jewels are both the currency and the upgrade tool for items in MU. This guide shows what each one does according to a Season 4 emulator's source code and compares the configured success rates across three versions.
What each main jewel does
The rules below were read from the source code of the MuBattle Season 4 emulator (MUemu family), which is open and used as a base by many servers. Other bases may differ slightly.
- Jewel of Bless: raises the item level by +1 while it is below +6. It never fails. It also restores Fenrir and pick axe durability.
- Jewel of Soul: tries to raise the item +1 up to +9. The chance comes from the server configuration and gets a bonus if the item has Luck. On failure, a +7 or higher item drops to +0; below that, it loses one level.
- Jewel of Life: raises the item's additional option by one step, up to the configured limit. On failure, the additional option resets to zero.
- Jewel of Chaos: the ingredient for the Chaos Machine, used for combinations (wings, Chaos items and other recipes).
Configured rates by version
The same jewel can have a different chance on each server. These are the values found in the emulator packages we document:
| Season 3 | Season 4 | Season 6 | Season 20 | |
|---|---|---|---|---|
| Soul success rate (%) | 50 | 50 | 100 | 50 |
| Luck bonus on Soul (%) | 25 | 25 | 25 | 25 |
| Life success rate (%) | 50 | 50 | 50 | 60 |
| Max additional option steps | 7 | 7 | 7 | 4 |
Values found in the GameServerInfo files of each emulator package we analysed. They are not official rules: every server sets its own.
How to use them without losing the item
- Use Bless up to +6: it never fails, so there is no risk.
- From +6 to +9, Soul risks the level. Items with Luck have a better chance.
- From +7 up, a failed Soul resets the item to +0. Think twice before risking an expensive item.
- Life only risks the additional option, not the item level.
All documented jewels
Jewels present in the item files of the versions we document:
FAQ
Can the Jewel of Bless fail?
Not in the Season 4 emulator code we analysed: it raises the item +1 while it is below +6.
What happens when a Jewel of Soul fails?
A +7 or higher item drops to +0. Between +1 and +6, it loses one level.
What is the Jewel of Soul success rate?
It depends on the server. In the packages we document the value found is 50% (Season 3, 4 and 20) and 100% (Season 6 LEGADO), with a bonus for items with Luck.
Play MU? MU Éter is a Season 4 server with its own systems. Discover MU Éter · MMO GRID is maintained by the MU Éter team.
Sources
- MuBattle Season 4 emulator source code (ObjectManager.cpp: CharacterUseJewelOfBles, CharacterUseJewelOfSoul, CharacterUseJewelOfLife)
- GameServerInfo - Common.dat from the Season 3, 4, 6 and 20 emulators
Demand snapshot: SNAP-20261001-1040 · Data extracted on 2026-10-01