Guide to finding gems on the auction house

All crafted socketable gems are named in a particular two-part pattern:

 

Where
 * 
 * A name that defines what stats the gem have. All gems with that name share those attributes, though the values will vary.


 * 
 * The base material used to make the (socketable) gem. The better the base material, the greater the resulting attributes.

Generally:
 * Gems introduced with Mists of Pandaria have better stats than those from Cataclysm, Wrath of the Lich King or Burning Crusade
 * Gems with a rarer item quality have better stats than those with lower quality.

To find the gem you want, you can search for the &lt;Stat_prefix&gt; part of the name, depending on what socket and stats you are looking for, then use the quality selector on the Auction House UI to specify what amount of the desired stats you want (and how much gold you are willing to spend). Alternately, you can choose in the subset of gem the color you want and specify the quality, then it will produce a longer list of gems you can choose from.

Patch 4.0.1 revised the gem system to be a little simpler. Several stats were removed along with existing stats being moved to a different color, causing the corresponding green, orange, or purple gem to either be removed, changed, or added. Biggest change was hit rating, intellect, and dodge rating moved to blue, red, and yellow (previously yellow, yellow, and red) respectively. Yellow stormjewels were removed and mastery rating will premiere on yellow gems for patch 4.0.3a.

Red Gems

 * Blood Garnet·Living Ruby·Crimson Spinel
 * Stormjewels·Bloodstone·Scarlet Ruby·Cardinal Ruby
 * Carnelian·Inferno Ruby·Queen's Garnet
 * Pandarian Garnet·Primordial Ruby

Blue Gems

 * Azure Moonstone·Star of Elune·Empyrean Sapphire
 * Stormjewels·Chalcedony·Sky Sapphire·Majestic Zircon
 * Zephyrite·Ocean Sapphire·Deepholm Iolite
 * Lapis Lazuli·River's Heart

Yellow Gems

 * Golden Draenite·Dawnstone·Lionseye
 * Sun Crystal·Autumn's Glow·King's Amber
 * Alicite·Amberjewel·Lightstone
 * Sunstone·Sun's Radiance

Purple Gems
"Matches a Red or Blue Socket."
 * Shadow Draenite·Nightseye·Shadowsong Amethyst
 * Shadow Crystal·Twilight Opal·Dreadstone
 * Nightstone·Demonseye·Shadow Spinel
 * Roguestone·Imperial Amethyst

Green Gems
"Matches a Blue or Yellow Socket."
 * Deep Peridot·Talasite·Seaspray Emerald
 * Dark Jade·Forest Emerald·Eye of Zul
 * Jasper·Dream Emerald·Elven Peridot
 * Alexandrite·Wild Jade

Orange Gems
"Matches a Red or Yellow Socket."
 * Flame Spessarite·Noble Topaz·Pyrestone
 * Huge Citrine·Monarch Topaz·Ametrine
 * Hessonite·Ember Topaz·Lava Coral
 * Tiger Opal·Vermilion Onyx

Meta Gems
While meta gems also use the " " naming scheme, there are many effect combinations, making a table by attributes impractical. See Meta gems for a full listing.
 * Earthstorm Diamond·Skyfire Diamond
 * Earthsiege Diamond·Skyflare Diamond
 * Starflare Diamond·Earthshatter Diamond (not crafted, can only be bought)
 * Shadowspirit Diamond
 * Primal Diamond

Pearls
Both of these can be crafted into purple 'Purified' gems (Spell Power and Spirit)
 * Jaggal Pearl·Shadow Pearl

Both of these can be crafted into prismatic Enchanted varieties that add a value to all stats.
 * Northsea Pearl·Siren's Tear

Enchanting created Gems
These grant additional resistance to all realms of magic.
 * Prismatic Sphere·[[Void Sphere}}