Quote (TheChosen @ Oct 25 2010 12:53pm)
1. Legit: An item is legit, by definition, if it has never been duped. It is an entirely unique, one-of-a-kind item with its very own item code (more on item codes later).
2. Perm: An item is perm, by definition, if it has been duped without an item code. In general, the only way this is possible is if the item was duped no later than the 1.09 patch. Starting with 1.10, Blizzard implemented item codes (again, more on this later). The exception to this rule is the duping of "virgin bases." If a white (normal) item is duped without ever having been made into a runeword, it will be perm. This is because only rare, magic, unique, and runeword items have item codes. If an item is made into a runeword and later cleared out with a hel rune, it still has an item code.
3. Item Code: Implemented by Blizzard in the 1.10 patch. Any items duped now will have identical item codes. Whenever 2 items with the same item code are in the same game (I believe it can even be on the same ip), they "clash" and "poof." This makes it impossible to perm dupe without altering item codes (some say certain sites can do this allowing them to perm dupe, I personally have no idea if this is true or not). Any item that was perm receives an item code identical to the new item and thus becomes unperm if it is duped. When clashing an item, you are attempting to find an unperm of the same item code, not merely the same name. Some people don't understand this very well, so here is an example:
In 1.09, a valk is duped. There are 5 copies, Valk A, Valk B, Valk C, Valk D, and Valk E. Valks A, B, C, and E are duped in patch 1.10. They are now unperm. Valk D, while still being a dupe, is not unperm because it does not have an item code that has any duplicates. Alternatively, the possessor of a duped "Valk A" might think their valk is, in fact, perm. They clash it against known unperm copies of Valks B, C, and E without any poofing. They need to clash it against another "Valk A" inorder to poof it.
Now multiply the number of post .09-duped valks, add the fact that you don't know which is which, and you will see why clash testing will never truly be effective in ascertaining an item's validity.
I would like to add that item codes are entirely different from item levels(ilvl), and there is no way to see an item's item code.[/B]
tl;dr