Legendary Gems

Legendary Gem upgrade interface via Urshi.

Legendary Gems will be added to Reaper of Souls in Patch 2.1, and are currently undergoing testing on the PTR. The items add special bonuses when socketed in rings and amulets (only on Chars and not on Followers), and can be upgraded in power via Urshi, the NPC who appears after Greater Rifts are cleared.

While the developers are calling them "legendary gems" these socketables have nothing in common with regular gems in stats or appearance, and are more analogous to the Rainbow Facet unique jewels of Diablo 2. The main difference in Diablo 3 is that these gems can only be socketed in jewelry, and the way the gems can be upgraded to improve their functions over time.

Legendary Gems Listing

While the Legendary Gems are still undergoing development on the PTR, their stats and bonuses are changing constantly. A major revision was created on July 15, 2014 with new or upgraded stats for almost every gem. ^[1] The following are the most current details about Legendary Gems.

Bane of the Powerful

Gain 30% increased damage for 20 seconds after killing an elite pack.
Upgrade rank grants: +1 second buff duration.
Rank 50 unlocks: Gain 20% bonus damage to elites.

Enforcer

Increase the Critical Hit Chance of your pets by 20%.
Upgrade rank grants: +0.4% Critical Hit Chance. Max +20% upgrade (+40% total).
Rank 50 unlocks: Your pets are unkillable.

Bliz Note: As was discussed in another thread, allowing this this gem to rank up to +100% pet Crit would likely cause undesired gearing issues and probably be a little out of line.

Moratorium

30% of all damage taken is instead staggered and dealt to you over 3 seconds.
Upgrade rank grants: +0.1 second to the stagger duration.
Rank 50 unlocks: 10% chance on kill to clear all staggered damage.

Zei’s Stone of Vengeance

Damage you deal is increased by 6% for every 10 yards between you and the enemy hit. Maximum 30% increase.
Upgrade rank grants: +0.1% for every 10 yards (+0.5% to max).
Rank 50 unlocks: 30% chance on hit to Stun the enemy for 1 second.

Bliz Note: The max of 50 yards was added not because it was too powerful (even though it was too powerful), but so that you wouldn't be incentivized to stay offscreen while your pets killed everything. At 50 yards, I expect you to be in range to actually still use your skills (crazy right?).

Simplicity’s Strength

Increase the damage of primary skills by 25%.
Upgrade rank grants: +0.5% damage.
Rank 50 unlocks: Primary skills heal you for 2% of maximum health on hit.

Bane of the Trapped

Increase damage against enemies under control-impairing effects by 20%.
Upgrade rank grants: +0.5% damage.
Rank 50 unlocks: Gain an aura that reduces the movement speed of enemies within 15 yards by 30%.

Wreath of Lightning

15% chance on hit to gain a Wreath of Lightning, dealing 500% weapon damage as Lightning every second to 1-2 nearby enemies for 3 seconds.
Upgrade rank grants: +10% weapon damage per second.
Rank 50 unlocks: While under the effect of the Wreath of Lightning, gain 25% increased movement speed.

Gem of Efficacious Toxin

Poison all enemies hit for 1000% weapon damage over 10 seconds.
Upgrade rank grants: +20% weapon damage over 10 seconds.
Rank 50 unlocks: All enemies you poison take 10% increased damage from all sources.

Pain Enhancer

Critical hits cause the enemy to bleed for 500% weapon damage as Physical over 3 seconds.
Upgrade rank grants: +10% weapon damage over 3 seconds.
Rank 50 unlocks: Gain Blood Frenzy, granting you 2% increased Attack Speed for each bleeding enemy within 20 yards.

Mirinae, Teardrop of the Starweaver

15% chance on hit to smite a nearby enemy for 1000% weapon damage as Holy.
Upgrade rank grants: +20% weapon damage.
Rank 50 unlocks: Smite a nearby enemy every 5 seconds.

Gogok of Swiftness

50% chance on hit to gain Swiftness, increasing your Attack Speed by 2% for 3 seconds. This effect stacks up to 10 times.
Upgrade rank grants: +1% chance.
Rank 50 unlocks: Gain 2% Cooldown Reduction per stack of Swiftness.

Invigorating Gemstone

While under any control-impairing effects, reduce all damage taken by 30%.
Upgrade rank grants: +1%. Maximum +50% upgrade (80% total).
Rank 50 unlocks: Heal for 20% of maximum life when hit by control-impairing effect.

Boon of the Hoarder

30% chance on killing an enemy to cause an explosion of gold.
Upgrade rank grants: +1% chance on kill.
Rank 50 unlocks: Gain 30% increased movement speed for 3 seconds after picking up gold.

Taeguk

Gain 1% increased damage for 4 seconds after spending primary resource. This effect stacks up to 10 times. Gaining a stack refreshes all existing stacks.
Upgrade rank grants: +1 max stack.
Rank 50 unlocks: Gain 1% increased Armor for every stack.

Bliz Note: This buff duration on this gem was chosen so that it’s easier to keep up with cheap spenders and not trivial with expensive spenders.

Gem Upgrade Odds

Legendary Gem upgrade interface from a L19 GRift.

The only way to upgrade a Legendary Gem is via Urshi, who only appears when a character defeats the Greater Rift Guardian after the 15 minute timer has expired. So players must fail to finish a Rift in time, but still continue on to clear it and kill the Guardian. (Who drops the same quality of loot in either case.)

The odds that a gem will be upgraded increase with each higher level Greater Rift completed in that game. There is also a chance that the gem will receive a double, triple, or quadruple upgrade, boosting it 1-4 levels in total. It's yet not known if anything effects the chances of a double or bigger upgrade, and most fans suspect it's pure RNG.

The Legendary Gem upgrade chances are displayed in the tooltip, so the following figures are not estimations, but are what the game actually says before each upgrade attempt.[1]

Rift Level 01 - Upgrade chance 21%
Rift Level 17 - Upgrade chance 45%
Rift Level 18 - Upgrade chance 46%
Rift Level 19 - Upgrade chance 47%
Rift Level 20 - Upgrade chance 49%
Rift Level 21 - Upgrade chance 50%
Rift Level 22 - Upgrade chance 51%
Rift Level 25 - Upgrade chance 55%
Rift Level 26 - Upgrade chance 56%
Rift Level 27 - Upgrade chance 57%
Rift Level 28 - Upgrade chance 58%
Rift Level 29 - Upgrade chance 59%
Rift Level 30 - Upgrade chance 60%
Rift Level 31 - Upgrade chance 61%
Rift Level 31 - Upgrade chance 62%
Rift Level 33 - Upgrade chance 63%
Rift Level 34 - Upgrade chance 64%
Rfit Level 35 - Upgrade chance 65%
Rift Level 40 - Upgrade chance 70%
Rift Level 41 - Upgrade chance 71%
Rift Level 45 - Upgrade chance 75%
Rift Level 50 - Upgrade chance 79%
Rift Level 69 - Upgrade chance 93%
Rift Level 100 - Upgrade chance 100%

Official Theorizing

Blizzard's John Yang explained the design theory behind Legendary Gems while they were being tested on the PTR, July 15, 2014. ^[2]

Hi everyone. I wanted to pop in here while discussion on Legendary gems is ongoing.

First off, our philosophy on Legendary gems is that, when you pick one up for the first time, you should immediately want to use it, assuming it’s for your build, since some gems don’t apply to all builds/needs. This puts a minimum bar on the starting power level. After that, the power increase per upgrade is directly related to the frequency of upgrading, which is closely tied to the Greater Rift reward scheme and is still being iterated on. In the end, we’d like gems to be infinitely upgradeable when it makes sense, but not be outrageous.

Additionally, all Legendary gems have been disabled for followers. These powers were not designed for followers in mind, and this way we can ensure the gems are of a high power level because you can only have 3 equipped. In the future, if followers need avenues of advancement we would likely make Legendary gems specifically designed for them.

Now for the details. The existing stats you see on Legendary gems on the PTR today are somewhat placeholder. So, to steer further discussion in a direction that’s more in line with the next PTR build, here are the freshly tuned numbers (with some of my notes) for each gem.

Official Reveal

Legendary Gems were first revealed in June 2014 and the first official info came from Blizzard's Patch 2.1 preview blog. ^[3]

Legendary Gems are still undergoing significant iteration at this time, so you won’t see them available on the PTR right away. The gist is that these gems are infinitely upgradeable, and provide special Legendary powers when socketed into the appropriate gear slot. They can only be socketed into Rings and Amulets, and can be upgraded by completing additional Greater Rifts. The higher you place in a Greater Rift, the more likely your gem will be successfully upgraded. We’ll have more details in the future as we continue development on these powerful baubles, so stay tuned!