Simple RAW for Pathfinder Thread V: Golarion Strikes Back

[Cieyrin]

A306:
Yes. You can do the same with headbands/belts granting bonuses to stats (+2 to +4 to +6) and any other direct numerical upgrade. You can also add other skills on top... but you cannot change the skill (ie +5 diplomacy to +10 bluff)

While accurate, some of those items don't have official versions with higher bonuses and are technically the realm of custom items, subject to GM approval. The formulas are simple enough, certainly, especially when it comes to skill bonuses, but definitely something to note.