Use Gemcutter's Prism on a Skill Gem to add 5% Quality, up to the ordinary 20% cap. A gem starting at 0% therefore needs four Prisms. The effect is skill-specific: each Skill and Spirit Gem page lists what its Quality changes. Support Gems cannot receive Quality directly. A Vaal Orb can raise or lower gem Quality by up to 10 points, with positive corruption results capped at 23%, but it also Corrupts the gem.
- Open the Skill Gem page and read its Quality effects before spending currency.
- Check the gem's current Quality in the Skills Panel.
- Finish ordinary Quality changes before using a Vaal Orb.
Quality is skill-specific. Depending on the gem, it can change damage, area, duration, speed, limits, ailment behavior, a secondary component, or another named property. The Skill page preserves the full 0% to 20% range and separates Quality effects from ordinary level scaling.
- Open the exact Skill or Spirit Gem page.
- Find Quality effects rather than the level table.
- Check every component when the Skill has multiple parts.
DirectorySearch every active and Spirit Skill Gem with its exact Quality effects.
MechanicCompare Quality rules across gems, weapons, armour, flasks, charms, and jewellery.
Right-click Gemcutter's Prism, then apply it to the Skill Gem. Each Prism adds 5% Quality and ordinary use stops at 20%. A gem at 0% needs four Prisms, 5% needs three, 10% needs two, and 15% needs one.
- Subtract the current Quality from 20.
- Divide the remaining amount by five.
- Stop when the gem reaches 20% Quality.
CurrencyAdd 5% Quality to a Skill Gem up to the ordinary cap.
Active Skill Gems and Persistent Skill Gems can have their own Quality bonuses. Support Gems cannot have Quality added to them. Skills granted directly by equipment use the equipment's Quality rules instead, so Gemcutter's Prism does not target the weapon, sceptre, wand, staff, or other item that grants the Skill.
- Use Gemcutter's Prism on a Skill Gem, not a Support Gem.
- Treat a Persistent Skill Gem as a Skill Gem with its own listed effect.
- Use the correct equipment Quality currency for an item-granted Skill.
DirectorySupport Gems modify other Skills but cannot receive ordinary gem Quality.
MechanicFind the correct currency and effect for each item type.
GuideKeep Skill, Support, and Spirit Gem families separate.
Gemling Legionnaire's Advanced Thaumaturgy gives Skill Gems an additional Quality effect; it does not increase the gem's displayed Quality number. Dialla's Desire grants +5% Quality to a compatible supported Skill while socketed. These benefits use the Skill's Quality scaling but remain separate from the permanent Quality stored on the gem.
- Check the standard Quality effect first.
- Check Advanced Thaumaturgy for its additional effect on the exact Skill.
- Treat support-granted Quality as conditional on that Support remaining active.
MechanicBrowse every exact additional Quality effect.
AscendancyCompare all Skills affected by Advanced Thaumaturgy.
SupportGrant +5% Quality to a compatible supported Skill.
A Vaal Orb can add or subtract up to 10 percentage points of Quality, with a positive result capped at 23%. It can instead change the gem level, add or remove a Support socket, or produce no visible change. Starting at 20% gives the best chance of reaching 23%, but the result is random and the gem becomes Corrupted, preventing further ordinary Gemcutter's Prism use.
- Reach 20% ordinary Quality first.
- Accept that Quality can fall instead of rise.
- Evaluate the complete corruption result, including level and sockets.
CurrencyApply a random corruption outcome to the Skill Gem.
GuideCompare the complete gem corruption outcome group.
MechanicUnderstand which later modifications remain possible.
Quality is not always damageRead the exact Skill page. Quality can improve area, duration, speed, limits, or another mechanic without changing the main damage value.
Four Prisms are needed only from 0%Each Prism adds 5%. Check the current Quality before spending another one.
Support Gems do not receive ordinary QualityA Support can grant Quality to its supported Skill, but Gemcutter's Prism does not add Quality to the Support Gem itself.
Corruption is not a guaranteed upgradeThe gem can lose Quality or receive a different outcome. Ordinary Gemcutter's Prism use is unavailable after corruption.
CurrencyAdd 5% Quality to a Skill Gem up to the ordinary cap.
CurrencyApply a random corruption outcome to the Skill Gem.
SupportGrant +5% Quality to a compatible supported Skill.
MechanicFind the correct currency and effect for each item type.
MechanicBrowse every exact additional Quality effect.
GuideFinish sockets before risking corruption.
DirectorySearch every active and Spirit Skill Gem with its exact Quality effects.
DirectorySupport Gems modify other Skills but cannot receive ordinary gem Quality.
GuideKeep Skill, Support, and Spirit Gem families separate.
AscendancyCompare all Skills affected by Advanced Thaumaturgy.
GuideCompare the complete gem corruption outcome group.
MechanicUnderstand which later modifications remain possible.
