Gem

Gems are small objects that grant bonuses when socketed into items. There are five types of gems in Diablo III; Amethysts, Diamonds (added in D3v2), Emeralds, Rubies and Topazes. The bonuses provided by gems increase with the rank of the gem and become quite substantial at the highest ranks.

Gems drop randomly from every sort of target; monsters, Elites, chests, barrels, etc. At least one and often several gems drop from special targets, such as Resplendent chests, Treasure Goblins, Horadric Caches, etc. Gems can be upgraded in rank by the Jeweler for a fee of gold and materials.

Though the Jeweler can always remove a gem from an item (for a fee) there is no way to add sockets to an item in Diablo 3. (Gems can also be removed from items by salvaging, though this permanently destroys the item.) Reaper of Souls added the Mystic Artisan, who can enchant items, rerolling one of the affixes and giving players a chance to add a socket by rerolling one of the primary affixes. (Secondary affixes can never be sockets.) This can be a difficult and expensive task, sometimes requiring many rolls and prayers to the gods of RNG.

Gems have no effect on the level requirement of an item, and and are thus one of the most useful twinks to boost the gear quality of a lower level character.

See the Gems Archive for details about gems from D3's development and for the different properties and costs from Diablo 3 vanilla
See the Diablo 2 Gems page for details on that game's seven types of gems.

Socketing Basics

The bonuses from gems are quite powerful, and a primary affix that adds socket(s) to an item is one of the most desired item properties. Sockets begin to appear in items around level 15 (a few legendary helms can have a socket at level 10-15), and in the end game a socket is considered all-but-mandatory in weapons. In weapon sockets, players generally socket Emeralds for Critical hit Damage. Rubies for +damage, or Diamonds for +Elite damage are less popular.

Weapons can only ever have 1 socket in Loot 2.0, though the Manticore crossbow sometimes rolled 2 sockets in Diablo 3 vanilla.

A socket in a helm is also very desired, and usually used to obtain +EXP% from a Ruby, +Life% from an Amethyst, or Reduced cooldown from a Diamond.

All other items with a socket are considered "other" in terms of the bonuses they provide, (+to a single stat or All Res from a diamond) and these include:

Chest armor: 1-3 sockets.
Pants: 1-2 Sockets.
1 socket: Rings, Amulets, Shields, Mojos, Sources, and Quivers.
- Several legendary items in Diablo 3 vanilla held a socket in other slotsbut these are not found in the Loot 2.0 version of those legendaries. (Ice Climbers boots and Tasker and Theo gloves.)

Upgrading Gems

Chipped gems drop starting around level 15, with the next highest quality gem beginning to fall about every 6th level higher, culminating in the Flawless Square, which drops from enemies around level 55-60. In Diablo 3 Gems can be upgraded all the way to rank 15, the Marquise, though this is a very long and expensive process, especially in D3v2 with no more Auction House. (Upgrading all the way to a Marquise gem in D3v2 requires a total investment of 9,280,000 gold and 2143 Flawless Square gems.)

Reaper of Souls ups the gem quality considerably, and while nothing changes from level 1-60, level 61 targets (monsters, chests, objects, treasure goblins, etc) drop rank 15 Marquise gems, with a chance for Rank 16 Imperial gems to drop on Master or higher difficulty. Gems in RoS can be upgraded to rank 19, Flawless Royal quality.

Gem upgrade costs have been tweaked several times. The entire system received an overhaul for D3v2, with much lower gold costs and an almost total removal of material components. It's much cheaper to make the highest level gems in Reaper of Souls than it was to make them in Diablo 3 vanilla, though the number of gems is the same, with 2 > 1 until Flawless Square and 3 > 1 at all levels above that.

See the Gems archive article for info about upgrade costs in earlier versions of Diablo 3.

To Create:	Materials Required	Cumulative Cost [e]
Chipped	N/A	Find them.
1 Flawed	10 gold 2 Chipped	Find them.
1 Regular	25 gold +2 Flawed	Find them.
1 Flawless	40 gold +2 Regular	Find them.
1 Perfect	55 gold +2 Flawless	Find them.
1 Radiant	70 gold +2 Perfects	Find them.
1 Square	85 gold + 2 Radiant	Find them.
1 Flawless Square	100 gold +2 Squares	Find them.
1 Perfect Square	5000 gold +3 Flawless Squares	5k gold (3 Flawless Squares)
1 Radiant Square	10,000 gold +3 Perfect Squares	15k + 10k = 25k (9 Flawless Squares)
1 Star	20,000 gold +3 Radiant Squares	25k x 3 = 20 = 95k gold (27 Flawless Squares)
1 Flawless Star	30,000 gold +3 Stars	95k x 3 + 30k = 315k gold (81 Flawless Squares)
1 Perfect Star	50,000 gold +3 Flawless Stars	315k x 3 + 50k = 995k gold (243 Flawless Squares)
1 Radiant Star	75,000 gold +3 perfect stars	3 x 995k + 75k = 3,060,000 gold (729 Flawless Squares)
1 Marquise Gem	100,000 gold +3 Radiant Stars	D3: 3 x 3,060k + 100k = 9,280,000 gold (2143 Flawless Squares) Find them level 61+ (RoS only).
1 Imperial Gem RoS only	200,000 gold +3 Marquise Gems	200k gold + 3 Marquise gems. (Will occasionally drop in Master+ difficulty.) (This level gem is required for enchanting legendary jewelry.)
1 Flawless Imperial Gem RoS only.	300,000 gold +3 Imperials	900k gold (9 Marquise Gems)
1 Royal Gem RoS only	400,000 gold +3 Flawless Imperial + 1 Death's Breath	3.1 million gold, 3 DBs (27 Marquise Gems)
1 Flawless Royal Gem RoS only	500,000 gold +3 Royal + 1 Death's Breath	9.8m gold, 9 DBs (81 Marquise Gems)

Gem Properties

Each type of gem provides different bonuses in the three types of items: weapons, helms, and "other." The properties are the same for every rank of the each type of gem; only the values increase. Gems of the same rank share the same graphic; only the color changes.

Gem Rank	Helm	Weapon	Other[e]
Chipped Gem	Amethyst: +5% Life Diamond: Reduces cooldown of all skills by 3.5% Emerald: +5% Gold Find Ruby: +5% Bonus Experience Topaz: +5% Magic Find	Amethyst: 2 Life per Hit Diamond: +2% Increased damage against Elites Emerald: +10% Critical hit Damage Ruby: +3 Damage Topaz: Ranged and melee attackers take 2 damage per hit.	Amethyst: +10 Vitality Diamond: +6 Resistance to all elements Emerald: +6 Dexterity Ruby: +6 Strength Topaz: +6 Intelligence
Flawed Gem	Amethyst: +6% Life Diamond: -4% cooldown of all skills Emerald: +7% Gold Find Ruby: +7% Experience Topaz: +7% Magic Find	Amethyst: 3 Life per Hit Diamond: +3% Damage to Elites Emerald: +15% Critical hit Damage Ruby: +6 Damage Topaz: 3 Thorns damage	Amethyst: +10 Vitality Diamond: +10 All Res Emerald: +10 Dexterity Ruby: +10 Strength Topaz: +10 Intelligence
Regular Gem	Amethyst: +7% Life Diamond: -4.5% cooldown Emerald: +9% Gold Find Ruby: +9% Experience Topaz: +9% Magic Find	Amethyst: 6 Life per Hit Diamond: +4% Damage to Elites Emerald: +20% Critical hit Damage Ruby: +9 Damage Topaz: 6 Thorns damage	Amethyst: +14 Vitality Diamond: +14 All Res Emerald: +14 Dexterity Ruby: +14 Strength Topaz: +14 Intelligence
Flawless Gem	Amethyst: +8% Life Diamond: -5% cooldown Emerald: +11% Gold Find Ruby: +11% Experience Topaz: +11% Magic Find	Amethyst: 10 Life per Hit Diamond: +5% Damage to Elites Emerald: +25% Critical hit Damage Ruby: +12 Damage Topaz: 10 Thorns damage	Amethyst: +18 Vitality Diamond: +18 All Res Emerald: +18 Dexterity Ruby: +18 Strength Topaz: +18 Intelligence
Perfect Gem	Amethyst: +9% Life Diamond: -5.5% cooldowns Emerald: +13% Gold Find Ruby: +13% Experience Topaz: +13 Magic Find	Amethyst: 15 Life per Hit Diamond: +6% Damage to Elites Emerald: +30% Critical hit Damage Ruby: +15 Damage Topaz: 15 Thorns damage	Amethyst: +22 Vitality Diamond: +22 All Res Emerald: +22 Dexterity Ruby: +22 Strength Topaz: +22 Intelligence
Radiant Gem	Amethyst: +10% Life Diamond: -6% Cooldowns Emerald: +15% Gold Find Ruby: +15% Experience Topaz: +15% Magic Find	Amethyst: 25 Life per Hit Diamond: +7% Damage to Elites Emerald: +35% Critical hit Damage Ruby: +18 Damage Topaz: 30 Thorns damage	Amethyst: +26 Vitality Diamond: +26 All Res Emerald: +26 Dexterity Ruby: +26 Strength Topaz: +26 Intelligence
Square Gem	Amethyst: +11% Life Diamond: -6.5% Cooldowns Emerald: +17% Gold Find Ruby: +17% Experience Topaz: +17% Magic Find	Amethyst: 35 Life per Hit Diamond: +8% Damage to Elites Emerald: +40% Critical hit Damage Ruby: +21 Damage Topaz: 50 Thorns damage	Amethyst: +30 Vitality Diamond: +30 All Res Emerald: +30 Dexterity Ruby: +30 Strength Topaz: +30 Intelligence
Flawless Square Gem	Amethyst: +12% Life Diamond: -7% Cooldowns Emerald: +19% Gold Find Ruby: +19% Experience Topaz: +19% Magic Find	Amethyst: 65 Life per Hit Diamond: +9% Damage to Elites Emerald: +45% Critical hit Damage Ruby: +25 Damage Topaz: 100 Thorns damage	Amethyst: +34 Vitality Diamond: +34 All Res Emerald: +34 Dexterity Ruby: +34 Strength Topaz: +34 Intelligence
Perfect Square Gem	Amethyst: +13% Life Diamond: -7.5% Cooldowns Emerald: +21% Gold Find Ruby: +21% Experience Topaz: +21% Magic Find	Amethyst: 105 Life per Hit Diamond: +10% Damage to Elites Emerald: +50% Critical hit Damage Ruby: +40 Damage Topaz: 200 Thorns damage	Amethyst: +38 Vitality Diamond: +38 All Res Emerald: +38 Dexterity Ruby: +38 Strength Topaz: +38 Intelligence
Radiant Square Gem	Amethyst: +14% Life Diamond: -8% Cooldowns Emerald: +23% Gold Find Ruby: +23% Experience Topaz: +23% Magic Find	Amethyst: 190 Life per Hit Diamond: +11% Damage to Elites Emerald: +60% Critical hit Damage Ruby: +60 Damage Topaz: 350 Thorns damage	Amethyst: +42 Vitality Diamond: +42 All Res Emerald: +42 Dexterity Ruby: +42 Strength Topaz: +42 Intelligence
Star Gem	Amethyst: +15% Life Diamond: -8.5% Cooldowns Emerald: +25% Gold Find Ruby: +25% Experience Topaz: +25% Magic Find	Amethyst: 300 Life per Hit Diamond: +12% Damage to Elites Emerald: +70% Critical hit Damage Ruby: +80 Damage Topaz: 600 Thorns damage	Amethyst: +46 Vitality Diamond: +46 All Res Emerald: +46 Dexterity Ruby: +46 Strength Topaz: +46 Intelligence
Flawless Star Gem	Amethyst: +16% Life Diamond: -9% Cooldowns Emerald: +27% Gold Find Ruby: +27% Experience Topaz: +27% Magic Find	Amethyst: 400 Life per Hit Diamond: +13% Damage to Elites Emerald: +80% Critical hit Damage Ruby: +100 Damage Topaz: 900 Thorns damage	Amethyst: +50 Vitality Diamond: +50 All Res Emerald: +50 Dexterity Ruby: +50 Strength Topaz: +50 Intelligence
Perfect Star Gem	Amethyst: +17% Life Diamond: -9.5% Cooldowns Emerald: +29% Gold Find Ruby: +29% Experience Topaz: +29% Magic Find	Amethyst: 500 Life per Hit Diamond: +14% Damage to Elites Emerald: +90% Critical hit Damage Ruby: +130 Damage Topaz: 1250 Thorns damage	Amethyst: +54 Vitality Diamond: +54 All Res Emerald: +54 Dexterity Ruby: +54 Strength Topaz: +54 Intelligence
Radiant Star Gem	Amethyst: +18% Life Diamond: -10% Cooldowns Emerald: +31% Gold Find Ruby: +31% Experience Topaz: +31% Magic Find	Amethyst: 600 Life per Hit Diamond: +15% Damage to Elites Emerald: +100% Critical hit Damage Ruby: +160 Damage Topaz: 1800 Thorns damage	Amethyst: +58 Vitality Diamond: +58 All Res Emerald: +58 Dexterity Ruby: +58 Strength Topaz: +58 Intelligence
Marquise Gem Gem	Amethyst: +19% Life Diamond: -10.5% Cooldowns Emerald: +33% Gold Find Ruby: +33% Experience Topaz: +33% Magic Find	Amethyst: 700 Life per Hit Diamond: +16% Damage to Elites Emerald: +110% Critical hit Damage Ruby: +190 Damage Topaz: 2500 Thorns damage	Amethyst: +62 Vitality Diamond: +62 All Res Emerald: +62 Dexterity Ruby: +62 Strength Topaz: +62 Intelligence
Imperial Gem RoS only	Amethyst: +20% Life Diamond: -11% Cooldowns Emerald: +35% Gold Find Ruby: +35% Experience Topaz: +35% Magic Find	Amethyst: 3000 Life per Hit Diamond: +17% Damage to Elites Emerald: +115% Critical hit Damage Ruby: +220 Damage Topaz: 3100 Thorns damage	Amethyst: +100 Vitality Diamond: +66 All Res Emerald: +100 Dexterity Ruby: +100 Strength Topaz: +100 Intelligence
Flawless Imperial Gem RoS only.	Amethyst: +21% Life Diamond: -11.5% Cooldowns Emerald: +37% Gold Find Ruby: +37% Experience Topaz: +37% Magic Find	Amethyst: 6400 Life per Hit Diamond: +18% Damage to Elites Emerald: +120% Critical hit Damage Ruby: +220 Damage Topaz: 3725 Thorns damage	Amethyst: +160 Vitality Diamond: +70 All Res Emerald: +160 Dexterity Ruby: +160 Strength Topaz: +160 Intelligence
Royal Gem RoS only	Amethyst: +22% Life Diamond: -12% Cooldowns Emerald: +39% Gold Find Ruby: +39% Experience Topaz: +39% Magic Find	Amethyst: 8800 Life per Hit Diamond: +19% Damage to Elites Emerald: +125% Critical hit Damage Ruby: +250 Damage Topaz: 4350 Thorns damage	Amethyst: +220 Vitality Diamond: +74 All Res Emerald: +220 Dexterity Ruby: +220 Strength Topaz: +220 Intelligence
Flawless Royal Gem RoS only	Amethyst: +23% Life Diamond: -12.5% Cooldowns Emerald: +41% Gold Find Ruby: +41% Experience Topaz: +41% Magic Find	Amethyst: 11200 Life per Hit Diamond: +20% Damage to Elites Emerald: +130% Critical hit Damage Ruby: +270 Damage Topaz: 4975 Thorns damage	Amethyst: +280 Vitality Diamond: +78 All Res Emerald: +280 Dexterity Ruby: +280 Strength Topaz: +280 Intelligence