PoE Corrupt a gem to become either level 21 or 23% quality
To complete the PoE 3.28 challenge of obtaining a level 21 or 23% quality gem in Path of Exile, you must use a Vaal Orb on a level 20, 20% quality gem. The most efficient method for a 21/20 or 20/23 gem is using a Vaal Orb; for a 21/23 gem, use the Locus of Corruption (T3 Gem Room) in Alva’s Temple.