What should I skill up on?
There are two major standbys for leveling Jewelcrafting, Stone Statues and Trade Goods.
Those practically worthless stones that drop from mining nodes are converted into Stone Statues for a cheap Renew (10 hp/s for 15s at the Rough level up to 50 hp/s for 15s at the Dense level) and cheap Jewelcrafting levels.
Trade Goods are mats required for some of your Jewelcrafting recipes that are made from base metals, very similar to the clothcrafting or engineering schema in that at the "Copper" level you use the "Delicate Copper Wire" trade good in almost everything you do, and it uses 2 Copper Bars. So this is an item you can make for cheap skill that you will use to gain more skill, and is one of the only times in Jewelcrafting that Bars will be more important than Ore.
What should I stockpile now to level Jewelcrafting?
Given new recipe information, I would strongly encourage potential jewelcrafters to stockpile both Copper (at least 200) and Thorium Ore and Thorium-related gems. This will get you only to 300, at 300 you will need Outland materials pretty much in exclusivity.
How high can I get with materials from Azeroth?
310, this is pretty much the same for all other professions as far as I've seen.
What is Prospecting?
Prospecting is a skill that can be trained at level 20 Jewelcrafting from any Jewelcrafting vendor. It grants the Prospecting ability in your ability book. In game text:
Prospecting
2 sec cast
Search 5 ore of a base metal for precious gems. This will destroy the ore in the process.
The function is incredibly similar to Disenchant, it kills the ore but has a chance at returning materials used in your profession. In this case, gems.
What gems can be found with Prospecting?
From all testing so far, you can get any gem that is naturally found on the node of that ore type (eg Shadowgem from Copper, Citrine from Mithril, Azeorthian Diamond from Thorium, Flame Spessarite from Fel Iron)
Are there any restrictions to Prospecting
Two actually. First of all, as the description states you can only search ore of a base metal. This excludes noble metals such as Silver, Gold, Truesilver, Eternium, and Khorium (any ore with "green" rarity). Second, you must have Jewelcrafting skill roughly equivalent to the mining skill required to mine that ore (eg 175 for Mithril, 300 for Fel Iron, 350 for Adamantite)
I have a ton of gems, now what?
Below 300 Jewelcrafting skill, gems are only used as part of jewelry creations, and although you will need a lot of gems to skill up, they don't really take value until past 300.
Past 300, the Outland-exclusive gems can be "cut" into gems that can be added to socketable equipment.
Aren't socketable gems just portable enchants?
Gems are "portable" in the sense that a Jewelcrafter can cut a gem and sell it on the Auction House, but they have restrictions too. Gems can't be added to gear that does not have pre-existing sockets, enchants can be.
Can you socket AND enchant an item?
Yes, sockets are seperate from enchantments, you can use both on the same piece of gear. =)
Can you change gems in an item?
Yes, works just like enchantments. This means that your old "enchantment" (gem) is lost, but you can put a new one in no problem.
Can I stand in Orgrimmar all day cutting gems for people to make money?
EDIT: Yes. So far, ONLY meta gems have a cooldown on gem cutting, this cooldown is 1 hour and it does NOT affect the cutting of other Uncommon and Rare gems.
How do I cut gems?
Gem cutting requires a gem, a recipe for the specific "cut" of gem you're aiming for, and a Simple Grinder, which is just a trade item found on nearly any trade goods vendor for 2g50s.
What does specific cut mean?
As mentioned in the Jewelcrafting preview, there is more than one way to cut each type of gem. For example, a Golden Draenite can be cut Brilliant (+6 Intellect), Gleaming (+6 Spell Critical Rating), Thick (+6 Defense Rating), Rigit (+6 Hit Rating), or Smooth (+6 Critical Strike Rating), and these are just the ones we know of so far. Every cut requires a different recipe, so you can imagine already how many potential recipes there are!
Where do I find these recipes?
In the alpha, a small selection of gem cutting recipes have been placed on the Master Jewelcrafters in Thrallmar and Honor Hold. In the release, these recipes are designed to be world drops. I imagine some of them will be vendor-bought, but the vast majority of gem cuts will be found in the world. Additionally, there are some blue gem recipes that have so far been found only in Nagrand.