Crafting
Certain items you find or purchase from shops are craftable. Craftable items have additional attribute stats which are added as a bonus in addition to the normal stats and any hell forged stats. When you obtain an item which is craftable, these bonus stats are rolled randomly, so it may be great or poor.
Craft Levels
Craftable items are graded between Perfect and Very Poor as one of the following: Perfect, Excellent , Very Good , Average , Poor and Very Poor. If an item isn't graded yet, it is said to be Uncrafted.
Typically there is a range for each stat and craft level, so that it is not certain that two identical items with the same craft level has the exact same stats. The only exception to this rule is Perfect, which as the name implies is when all stats are maxed out on the item.
Crafting Items
In the crafting section of the game page you can pay a crafter some FSPs to have him re-craft your item. There are four different crafters available, charging between 1 and 5 FSP for the job. The more senior (and expensive) the craftman, the higher is your chance of obtaining a 'Perfect' item.
Another thing that affects your craft chances is the Master Crafter enhancement.