Crafted Items have 1-4 Random Magical Prefixes/Suffixes
On top of those fixed properties, a Crafted Item can have from 1-4 standard Rare and Magic Prefix and Suffixes. These are generated pretty much the same way as a Rare item.
At ilvls 1-30, there's a 40% chance of 1 affix and a 20% chance each of 2, 3 or 4 affixes.
At ilvls 31-50, there's a 60% chance of 2 affixes and a 20% chance each of 3 or 4 affixes.
At ilvls 51-70, there's an 80% chance of 3 affixes and a 20% chance of 4 affixes.
At ilvls 71+, there's a 100% chance of 4 affixes. 
----- I was wrong it's 71 not 85.
You can stack the "fixed" Magical Prefixes/Suffixes with regular Magical Prefixes/Suffixes that can appear on Rare Items to create bonuses that are much higher than would normally appear on a Rare Item. Note: this does not mean you will keep the Magical Bonuses on the item you place in the cube, this simply means that it's possible to combine the "fixed" Crafted Bonuses with normal Magic Prefixes and Suffixes.
To determine which pre- and suffixes can spawn on the Crafted Item the affix level has to be calculated. All pre- and suffixes with a level up to the calculated affix level can spawn on the Crafted Item.
The basis for the calculation of the affix level is the item level. The ilvl of a Crafted Item is equal to half the level of the crafting character (rounded down) plus half the ilvl of the input item (rounded down). Put another way:
(1) ilvl = int(.5 * clvl) + int(.5 * ilvl)
The ilvl calculated in (1) has to undergo two checks and possible modifications. First, ilvl is capped at 99:
(2) if ilvl > 99 then ilvl = 99
Then qlvl and ilvl are compared. The higher number is used for further calculations:
(3) if qlvl > ilvl then ilvl = qlvl
The final step is to determine the affix level. If the ilvl is smaller than 99 – int(qlvl/2) then the affix level is ilvl – int(qlvl/2). Otherwise the affix level is ilvl*2 – 99:
(4) if ilvl < (99 – int(qlvl/2)= then affix level = ilvl - int(qlvl/2) else affix level = ilvl * 2 - 99.
It's also worth noting that the ilvl, the quality and the properties of the jewel are completely irrelevant and don't affect the outcome at all.
The Blood Weapon Recipe is used to craft a Berserker Axe (qlvl = 86) that was dropped by a monster in the Worldstone Tower in hell difficulty (ilvl = 85). The character used for crafting has level 78 (clvl = 78).
First, ilvl has to be calculated: ilvl = int(.5 * 78) + int(.5 * 85) = 39 + 42 = 81.
Then it's checked if the calculated ilvl is higher than 99. This is not the case, so ilvl remains 81. But qlvl 86 is higher than ilvl 81, so the ilvl is set to 86.
Finaly, the affix level can be determined: Since 86 is not smaller than (99 - int(86 / 2)) = 56 the affix level is ilvl * 2 - 99, in our example 86 * 2 - 99 = 73.
So all pre- and suffixes with a level up to 73 can spawn on the Crafted Item.
Note: Since the qlvl of amulets is 1 the term int(qlvl/2) is always 0, so the affix level is effectively determined by ilvl, so affix level = ilvl = int(.5 * clvl) + int(.5 * ilvl).
This post was edited by GodlyMe on Feb 26 2009 04:52pm