Gems

Gems are a type of socketable item found in Diablo II, its expansion, and Diablo III. These precious stones embody innate magical abilities. When set into a socketed item, these gems can add powerful magic effects. Higher grades of gems have stronger effects.

Diablo II
Gem effects are stackable, e.g. If you place 3 gems of the same type in a sword, you will receive the bonus of all three. The first gem that is placed will determine the color of the weapon.

They can only be obtained by killing monsters, opening chests or using a Gem Shrine with no other gem in your inventory. Vendors do not normally sell gems, though if another player in a multiplayer game sells a gem to a vendor, you may be able to buy it. Vendors also will not typically pay you full price for socketed items.

Once inserted, gems cannot be removed from a socket, although they can be destroyed via a Horadric Cube recipe. The skulls of some demonic creatures, inscribed with eldritch symbols, are said to work much like gems. They were introduced to showcase the socketing system, which was expanded in the Lord of Destruction with the introduction of Runes and Jewels.

There are six types of gems, plus skulls, which are considered by the game to be gems for all purposes:


 * Amethyst
 * Diamond
 * Emerald
 * Ruby
 * Sapphire
 * Topaz
 * Skull

They come in five levels of increasing quality, which also determines their sell price to vendors:


 * Chipped (250)
 * Flawed (750)
 * Normal (2,500)
 * Flawless (5,000)
 * Perfect (15,000)

You can upgrade gems by using a Gem Shrine, with a gem in your inventory, or by using the Horadric Cube. You can use the Horadric Cube to convert gems into higher quality gems. Place 3 gems of one type into the Horadric Cube and click the Transmute button.

Diablo III
In Diablo III, there are five different types of gems:
 * Amethyst (Life, Life per Hit or Vitality)
 * Emerald (Gold Find, Critical Damage or Dexterity)
 * Ruby (Experience Gain, Damage or Strength)
 * Topaz (Cost Reduction, Thorns Damage or Intelligence)
 * Diamond (Cooldown Reduction, Elite Damage or Resistance)

They come in ten (nineteen before patch 2.3) levels of increasing quality. They are free to put into sockets, but have a gold cost to remove from sockets. The costs to unsocket a particular quality is also listed below (listed per gem, that is, each additional gemmed socket increases cost accordingly). Alternatively, if the item itself is no longer needed, it can be salvaged, and gems will be returned to inventory free of charge.

As of Patch 2.5.0, all gems are free to unsocket with no gold cost. This can still only be done by the Jeweler.

Costs for unsocketing gems prior to Patch 2.5.0;

In Diablo III, the player upgrades gems through interaction with Covetous Shen, a jeweler. He will combine gems (2 gems for Regular-Star, 3 for higher ranks, Death's Breath also required for Royal and above) for an increasingly higher price, depending on the quality. Shen also offers to remove socketed gems from items, without destroying either one, also for a price.

Players with access only to the storyline provided by the original Diablo III can freely obtain gems of Chipped-Marquise tier, but require Reaper of Souls if they wish to go further; the Imperial gems and their better counterparts require a lv. 11+ Jeweler and a hero at level 61+, both of which are legitimately impossible to obtain without the expansion pack.

There is also an interesting workaround for those who wish to save their gold on unsocketing. If the items containing the gems desired are not planned to be of use anymore, the player can salvage those items at the blacksmith. The gems are safely returned, free of charge, in addition to receiving the salvaging material appropriate for the item salvaged.

Note that all gems of Marquise quality and above are account-bound, regardless of if they were dropped or crafted. This restriction is worsened if players play in a season; even a lowly Chipped gem will become bound to the account of the hero it dropped for.

As of patch 2.2.0, picking up a gem also picks up all other gems of any type within 20 yards.

Upgrade cost
Tables below represent the resources required for upgrading Gems to each tier of higher quality.

2 x Regular ->        Flawless:          2.5k 2 x Flawless ->       Square:              5k 2 x Square ->         Flawless Square:    10k 3 x Flawless Square -> Star:              20k 3 x Star ->           Marquise:           25k Marquise is the highest dropped quality available at level 60.

The next table shows the cumulative cost in gold and materials for higher quality gems. For the purposes of this table, Gems will refer to Marquise quality gems. DB will represent Death's Breath needed.

3 x Marquise ->         Imperial: 200k                                  (3 Gems) 3 x Imperial ->         Flawless Imperial: 200k * 3 + 300k = 900k       (9 Gems) 3 x Flawless Imperial -> Royal: 900k * 3 + 400k +1 DB = 3100k           (27 Gems, 1 DB) 3 x Royal ->            Flawless Royal: 3100k * 3 + 500k + 3 DB = 9800k (81 Gems, 4 DB)

A special note to be taken into consideration is that the table covering Reaper of Souls gem costs assumes that the player does not venture into Master or Torment difficulty. These difficulties offer a chance at Imperial quality gems dropping in addition to Marquise quality gems, drastically reducing costs and effort required to craft higher tier gems.

Also note that enchanting jewelry requires gems instead of gold; one Imperial gem of random type per attempt is required at level 70.

Effects
This table provides an overview of gem effects. For a detailed list of the power of the effects, please see the individual gem pages.

* At level 70, +% Bonus Experience is reduced to 10% effectiveness. (2.4.0 patch notes)

Legendary Gems
Legendary Gems were added in the 2.1 update. They resemble the Jewels from the second game, and are only socketable in amulets and rings, to a maximum of 3 per character (the only exceptions are Gem of Ease, which must be socketed into weapons instead, and Red Soul Shard, which only fits for Helms).

Their intended source are Rift Guardians in Greater Rifts, but one of them drops from Greed, and Red Soul Shard is obtained in Anniversary Dungeon.

Any one character can not receive any gem that he\she already has in his\her possession or in shared stash (however, this can be easily bypassed by storing the excess of gems on other characters). They are also unique-equipped, and two identical Legendary gems cannot be taken.

These gems can be upgraded by speaking with Urshi, who will appear in the Greater Rift after the Rift Guardian has been defeated. It does not cost anything to upgrade the gem. The blue numbers in a property on the gem are the only values that will be upgraded. The upgrade success rate depends on the current rift rank and the rank of the gem. When the gem reaches rank 25, it will gain a secondary (unupgradeable) power. A total number of upgrade attempts is 3 per run, 1 more can be purchased for gold via Empowered Rift, and additional 1 attempt is rewarded for a "clean" run with no deaths.