Violet Eye (H)
The Violet Eye is the faction associated with the raid instance, Karazhan. It's an introductory raiding environment for level 70s, generally well-geared from level 70 dungeons and even heroics. Because of this, you won't be able to work on this reputation right away, and you'll need to at least be associated with a guild that runs it regularly.
This is also the only faction with which you could theoretically stop grinding reputation at honored, for purely professional reasons, although you'll probably reach exalted anyway because of the loot, badges, and other reputation rewards.
The recipes available from this faction all feature stamina and frost resistance, and [Design: The Frozen Eye] is no different. It's a bind-on-equip purple, so you can make it on commission as well as for yourself.
Check out our class guides to gearing your character for Karazhan!
Thrallmar or Honor Hold (R)
As early as friendly, you'll receive a marketable cut featuring defense and stamina, [Design: Enduring Deep Peridot]. This will be a great way to make a few gold on the side. This design is also featured in Insider Trader: Jewelcrafting, the final stretch part 2, our guide to reaching skill level 375.
Although you get no designs at honored, once you hit revered you can purchase [Design: Dawnstone Crab]. A bind on pick-up blue trinket, this one is all for you, assuming that you're a tank of course.
Lower City (R)
Grinding reputation with Lower City can be a bit of a pain, but it is worth it. Do all of the quests in Terokkar and the Bone Wastes, taking special care to hand in Arakkoa Feathers you pick up from killing the Arakkoa first. After that runs out, the Auchindoun dungeons and their associated quests will help you work your way up the social ladder.
At friendly, you'll receive a nice caster cut, [Design: Potent Flame Spessarite]. While there is nothing to purchase at honored, three designs are unlocked at revered, two of which are bind on pick-up.
[Design: Felsteel Boar] is another blue trinket that only you can equip, although it is really only worth it if you stack attack power, despite the fighting boar that it will summon.
[Design: Pendant of Thawing] would go nicely with [The Frozen Eye] mentioned in the Violet Eye section, for fights requiring frost resistance. In fact, the use effect makes it all the more handy in parties, as it will block frost damage done to all party members. This is bind on equip, so you can make it to sell or pass around to guildmates and co-ordinate the usage in a raid.
[Design: Falling Star] is an epic gem cut, although you unfortunately cannot sell it, as the stone becomes bound to you once it is made. Still, as it awards 18 stamina, jewelcrafters of most, if not all, classes will find this useful.
Aldor or Scryers (R)
Unfortunately, you must choose between allying with the Scryers and the Aldor, and doing so will cut off your access to any designs that they might award you based on your reputation.
The Aldor offer three designs, one at friendly, one at honored and one at revered. [Design: Gleaming Golden Draenite] is therefore easy to acquire, and great for leveling your skills. Next, [Design: Royal Shadow Draenite] is a nice, marketable healing cut. Neither of these should sway your vote towards the Aldor, considering you can cheaply purchase the cut gems on the auction house from other jewelcrafters.
At revered, you'll be able to purchase [Design: Pendant of Shadow's End]. Extremely similar to [Design: Pendant of Thawing], it differs in that it protects from shadow instead of frost. This is a bind on equip blue necklace, and therefore, if you wanted to pledge allegiance to the Scryers, you would still have access to the finished product on the auction house.
The Scryers offer three designs that mirror those of the Aldor. At friendly, you may purchase a simple green cut, [Design: Runed Blood Garnet]. At honored, you gain an additional green cut, [Design: Dazzling Deep Peridot].
Once revered, you can purchase [Design: Pendant of Withering]. This one is based around nature resistance, rather than shadow or frost, but is otherwise the same, except of course, in the materials required to make it. Again, it is a bind on equip blue and should not necessarily influence your decision to choose Scryers over Aldor, or vice versa.
In fact, you could probably trade necklaces with a jewelcrafter allied with the opposing faction, provided the primals on your server sell for roughly the same amount of gold in each recipe.
The Sha'tar offers five different designs for your crafting pleasure. [Design: Insightful Earthstorm Diamond] is a meta gem cut that is available at friendly! This is great because it allows you to start profiting from meta cuts right away. Once you've scoped out the market, you may find that you can more reliably count on the success of meta sales than of green cuts.
[Design: Ring of Arcane Shielding] is a PvP, bind on equip blue ring, providing arcane resistance as well as resilience. If mages are the bane of your existence in battlegrounds or duels, or even while farming, this ring will come in handy. This is available at honored.
[Design: Kailee's Rose] can be purchased at honored as well, and is an invaluable reason for healers to choose jewelcrafting. This bind on pick-up purple gem is my new reason to wish I could have a third profession.
At revered, you will gain access to a new blue, bind on pick-up trinket, [Design: Talasite Owl]. If you have mana problems while you farm, for example, this should prove useful.
Also at revered comes [Design: Blood of Amber], another epic gem cut that only you may slot.