This guide is to help you Power Level one of the more costly professions as easily and cheaply as possible.
There is already a guide on the Blizzard forums, however I find that guide to be out of date and rather vague. I would like to help new JCs do it the easiest way possible. I have now leveled 5 JCs to 450. I have learned and imo perfected Power Leveling JC. Below are some of the ins and outs of leveling this profession.
The best way to do this is to have one character that can mine and spend at least one day mining like no tomorrow. However even with a miner you are going to need to purchase gems simply because prospecting is not that reliable. Case in point, I needed Citrine earlier and I had 5 stacks of Iron I just mined. Out of all of those stacks I prospected almost 70% Lesser moonstones. Prospecting helps but try not to rely on it.
Plan ahead- This is pretty straight forward. If possible plan ahead and watch the AH, it fluctuates greatly, sometimes prices stay at impossible levels while other times it can change over night. The best Gems to look for are Citrine, Moss agate, Aquamarine, Blue Sapphire, Azerothian diamonds, Star Rubies. Watch the AH and pick them up whenever the price plummets.
Planning ahead can save you a thousand gold or more. I am by no means saying that gem prices will always plummet. They will not, but you can circumvent these by carefully studying your options. The guide on the Blizzard forums gives you one single path to follow, this is not the best way to Power level JC unless you have a Dragon size horde of gold at your disposal.
The very first time I power-leveled JC I followed that guide to the letter, now on my 5th JC I look back and think...wow I was goofy for not thinking for myself.
Which recipe is the right recipe? The right recipe always depends what gems you have and what gems are available on the AH for reasonable prices. What I like to do is have one character in the field mining, one sitting at the AH and the JC siting at the trainer in Dalaran. This way you can keep bouncing back and forth as needed to see which is the cheapest possible avenue to take.
The greatest key to leveling JC is to always pay attention to higher level recipes and work towards those as cheaply as possible. Example: I scroll through the trainers recipes for ones that I know are cheapest and easy to make such as Solid stone statues, which can be bought for a gold or so a stack most of the time. If you blindly buy recipes you are costing yourself a ton of gold.
I will list below the only recipes I have learned and used so far. This last effort to level to 300 (so far) has been the cheapest yet and it all comes down to experience with leveling it. Well thankfully for you I am passing this along to save you from making the mistakes me and probably many others made as well.
Ring of Silvery Might
Heavy Jade ring
Pendate of the agate shield (purchased at one vendor per faction limited)
Citrine ring of rapid healing
Aquamarine pendant of the warrior
Ruby ring of destruction
Ruby pendant of fire
Truesilver healing ring
Simple Opal ring
Diamond focus ring
Sapphire pendant of winter night
Emerald lion ring
Addendum: I normally use Moss Agates but this time around I didnt get many mining or prospecting so I circumvented Moss agates however I could. Bothersome but not at all a show stopper. It just goes to show you that if you really put your mind to it you can avoid a lot of gold loss by buying mats a head of time or just working around a grossly overpriced gem or mat.
The above list is pretty solid and I use it a lot, but like I said the amounts will never ever be the same when leveling JC. It always depends on which gems I have or are available at reasonable prices on the AH.
Some items to keep an eye if you plan to level JC in the future are Essence of Undeath (grab at least 15 of these) And Heart of the Wild. Those two mats are prime example of what I am trying to explain in this guide. Last time I leveled JC Essence of Undeath were 1g per. However the next time they were 8g per. Last time I leveled JC ( month ago) Star rubies were 25g per, tonight they were 2g per. Same with Blue Sapphires, I bought 30 of these for around 40g, last time they were 5g per.
In the end it's not about a set list to follow, it's about what is avaible and for what price. This will vary greatly which makes it pretty much impossible to make a JC guide that says: make this X amount of times then make this X amount of times unless like I mentioned earlier, you have a ton of gold to burn and dont mind burning it.
Closing comment: When it's all said and done at the end of the day the very best advice I can offer you is to plan ahead when you know you are going be power leveling JC. The AH prices can change drastically and this one single detail can save you a thousand gold or more.
I hope this tutorial helps.