Maximum Possible
Gloves: 99
Legs: 135
Chest: 147
Helmet: 111
Class Item: 60
Ghost: 60
Artifact: 131
To calculate quality (% of max possible) add one high stat and one low, for example:
Int 60/85
Dis 57/82
85+57=142
Divide result by max (chest armor example):
142/147=96.59
Then round down:
96% of max possible quality