Veiled Nightseye

New rare gems with 2.1:

Yellow:

Great Dawnstone (8 Spell Hit Rating)
http://www.wowhead.com/?item=31861

Orange:

Veiled Noble Topaz (4 Spell Hit Rating | 5 Spell Damage)
http://www.wowhead.com/?item=31867
Wicked Noble Topaz (4 Critical Strike Rating | 8 Attack Power)
http://www.wowhead.com/?item=31868

Purple:

Balanced Nightseye (8 Attack Power | 6 Stamina)
http://www.wowhead.com/?item=31863
Infused Nightseye (8 Attack Power | 2Mp5
http://www.wowhead.com/?item=31865

Meta:

Thundering Skyfire Diamond (Melee/Ranged Haste Rating Proc)
http://www.wowhead.com/?item=32410
Relentless Earthstorm Diamond (+12 Agility | 3% Increased Critical Damage)
http://www.wowhead.com/?item=32409

All designs for these new gems are random world drops, only the Relentless Earthstorm Diamond is obtained from the Consortium Quartermaster once you reach exalted.

This is quoted from tivelositos from the sticky in the mage forums by Swindy, possibly one of the most helpful people to mage damage calculations in TBC

"So lets convert those formulas to a real world example. Let's take a fire mage with 900 spelldamage, 100 hit rating, and 30% to crit with fire.

+50 spell damage would mean (B+c*(D+n))/(B+c*D) = (902.5+1.035*(900+50)) / (902.5+1.035*900) = 1885.75 / 1834 = 1.0282 which is 2.82% more DPS.

+50 spell crit rating would translate to 2.26244 more crit chance (1.1*(C+n)+1) / (1.1*C+1) = (1.1*(0.3+0.0226244)+1) / (1.1*(0.3)+1) = 1.35488684 / 1.33 = 1.0187 which is 1.87% more DPS.

+50 spell hit rating is 3.96825 more hit chance on top of the 7,93651 hit chance the mage allready has (0.83+H+n)/(0.83+H) = (0,83 + 0,0793651 + 0,0396825)/(0,83+0,0793651) = 0,9490476/0,9093651 = 1,0436 meaning a whoping 4,36% more increase in DPS!"

Best raiding DPS caster gem period as of right now.