Buying Gems off the Auction House
You can make some gold off buying gems on the AH. And you don’t need to be a Jewelcrafter!
If Your a Jewelcrafter, and you don’t like the prospecting gamble, you can usually buy/bid on rare quality gems, cut, and resell for more. One of my biggest profit margins and quickest sellers are Scarlet Ruby cuts ( Bright, Bold, Delicate, and Runed). I can usually buy them for 80g and resell them cut for 100g +. My other one is Solid Sky Sapphires. I can purchase these for 10g and resell fro 25-30g.
But what if your not a Jewelcrafter, how can you make gold off buying gems? Check out Rare gems from BC. They vendor for 3g each, and since people are dumping them, you can buy/bid cut and non cuts for less than that. Vendor them and you have made a quick amount of gold.
You can do the same with Forest Emeralds. Since there is a large supply on my server and very little demand they usually have bid prices of 2.5g, I bid and win about 10-20 a day making about 5-10 g in a matter of 1-2 min. You can make even more on them if you are a Jewelcrafter since a cut version vendors for 4.5g.