Meta gems
1. Austere Earthsiege Diamond (629p) Rare
The boss tanking meta gem. Scales directly with the quality of your gear. No reason not to have this as your primary meta gem.
2. Eternal Earthsiege Diamond (384p) Rare
This meta gem is kind of a joker. The benefit from using it scales with how much Strength, Block Value, and Block Chance you have. Certainly the meta gem to use if you have a dedicated “TPS” tanking hat. For non-raid tanking where mobs don’t hit so hard, this meta gem will most likely be one offering the most damage reduction.
3. Effulgent Skyflare Diamond (322p) Rare
Interesting gem that besides adding Stamina also reduces spell damage taken. Its use seem pretty situational though.
4. Powerful Earthsiege Diamond (322p) Rare
Unless all bosses are spamming stuns, I don’t think a tank will find much use of this meta gem.
Normal gems
1. Solid Dragon’s Eye (271p) Epic Blue
2. Thick Dragon’s Eye (212p) Epic Yellow
3. Solid Majestic Zircon (198p) Epic Blue
4. Enduring Eye of Zul (178p) Epic Blue / Yellow
5. Regal Dreadstone (177p) Epic Red / Blue
6. Flashing Dragon’s Eye (169p) Epic Red
7. Defender’s Dreadstone (162p) Epic Red / Blue
8. Solid Sky Sapphire (159p) Rare Blue
9. Stalwart Flawless Amertrine (156p) Epic Red / Yellow
10. Shifting Dreadstone (156p) Epic Red / Blue
11. Thick King’s Amber (156p) Epic Yellow
12. Subtle Cardinal Ruby (156p) Epic Red
13. Delicate Dragon’s Eye (153p) Epic Red
14. Enduring Forest Emerald (142p) Rare Blue / Yellow
15. Regal Twilight Opal (142p) Rare Red / Blue
16. Glimmering Flawless Ametrine (141p) Epic Red / Yellow
17. Defender’s Twilight Opal (129p) Rare Red / Blue
18. Guardian’s Dreadstone (126p) Epic Red / Blue
19. Flashing Cardinal Ruby (125p) Epic Red
20. Stalwart Monarch Topaz (125p) Rare Red / Yellow
21. Shifting Twilight Opal (125p) Rare Red / Blue
22. Thick Autumn’s Glow (125p) Rare Yellow
23. Subtle Scarlet Ruby (125p) Rare Red
24. Delicate Cardinal Ruby (113p) Epic Red
25. Glimmering Monarch Topaz (112p) Rare Red / Yellow
26. Resolute Flawless Ametrine (105p) Epic Red / Yellow
27. Sovereign Dreadstone (105p) Epic Red / Blue
28. Guardian’s Twilight Opal (101p) Rare Red / Blue
29. Flashing Scarlet Ruby (100p) Rare Red
30. Forceful Eye of Zul (99p) Epic Blue / Yellow
31. Delicate Scarlet Ruby (91p) Rare Red
32. Resolute Monarch Topaz (84p) Rare Red / Yellow
33. Sovereign Twilight Opal (84p) Rare Red / Blue
34. Champion’s Flawless Ametrine (83p) Epic Red / Yellow
35. Enchanted Tear (77p) Rare Red / Blue / Yellow
36. Precise Dragon’s Eye (72p) Epic Red
37. Champion’s Monarch Topaz (67p) Rare Red / Yellow
38. Glinting Flawless Ametrine (57p) Epic Red / Yellow
39. Precise Cardinal Ruby (54p) Epic Red
40. Chromatic Sphere (51p) Rare Red / Blue / Yellow
41. Precise Scarlet Ruby (43p) Rare Red
42. Accurate Flawless Ametrine (27p) Epic Red / Yellow
43. Accurate Monarch Topaz (22p) Rare Red / Yellow
44. Bold Dragon’s Eye (14p) Epic Red
45. Bold Cardinal Ruby (11p) Epic Red
46. Bold Scarlet Ruby (9p) Rare Red
47. Fierce Flawless Ametrine (6p) Epic Red / Yellow
48. Etched Flawless Ametrine (6p) Epic Red / Yellow
*From: http://www.tankspot.com/forums/f97/39462-wotlk-tanking-gear-list.html