When crafting in Aion you have a chance to "proc" an item. What this means is you will originally be crafting say white(in quality) pants. Then they proc into Green(in quality) pants. When it procs it improves the stats and quality level of the item. You can also proc a Green item into a Blue item and so on and so forth until the item level cannot be improved or you can't use it in a craft.
You can tell you proc'd an item because the items name will turn green and the icon of it while crafting it will flash. After this happens you will continue to create the item like normal.