'Perfect' gold ore is the same as regular gold ore. The differences are only seen by Avan from Family Crest quest. He will say that he'll give you his piece of the Crest if you make him a necklace and ring made from a 'perfect gold bar' with rubies in them.
Smelting 'Perfect' gold ore while wearing the Goldsmithing gauntlets received after the quest will result in the standard double experience (56.2 exp with the gauntlets, rather than 22.5 from smelting it normally).
Unlike regular gold, however, 'perfect' gold ore cannot be used to make any jewellery other than those items used in the quest (that is, the Perfect necklace and the Perfect ring). If you attempt to make any other type of jewellery, the game will display the message "You can't make that with Perfect Gold." in the chat window.