Okay I will now explain how to create gems from normal items.
This is very simple but I only tested it once yet, so more might be possible.
At first you should run World of Warcraft. Download Cheat Engine and run it. You require 5.4 or higher, whit 5.3 you cannot select the process. Select the wow.exe process.
From now on I will tell what I did rather then what you should do.
I took an useless blue item from my inventory and searched for its identity. The item was a Cloak of Healing Rays - Item - World of Warcraft (Cloak of Healing Rays), and changed its identity to one of a gem, in this case Bold Crimson Spinel - Item - World of Warcraft (Bold Crimson Spinel). Now I was able to place the Cloak of Healing Rays on to one of my items. After I socketed it it changed, weirdly enough, into a Red Bryanite of Strength stuff (Red gem that gives +8 strenght).
When i searched WoWHead for it I couldnt find it, but later on more unknown sites I did. The reason why it changed into a red gem is not hard to guess. Because I replaced the identity of the Cloak of Healing Rays whit one of a red gem (Bold Crimson Spinel), it changed into an red gem, in this case Red Bryanite of Strength stuff. What I think is that if you replace an item identity whit a blue gem, you get the same effect but this time you get a blue gem, the Blue Bryanite of Agility (Blue gem that gives +8 agility). And ofcourse, if you replace the identity whit a yellow gem you get a yellow gem, the Yellow Bryanite of Stamina (Yellow gem that gives +8 stamina, the least usefull in my oppinion).
You should be able to do this whit any item. Tried it whit an Epic item too and it had the same effect, so the item you use shouldnt matter (useless items are best used). I do not yet know what happens when you use the identity of a meta gem or any other combination gems like a green gem. Workes on WoWBeez 2.4.
EDIT: It seems to be that you always get a Red Bryanite of Strength stuff