Note: as of Game Update 1.0.2, Gold Essence has been replaced by Gold Dust.
Gold Essences are one of the ingredients used in the Crafting Skill Talisman Making. Gold Essences are either crafted by an Apothecaries or sold by Merchants. For an Apothecary to craft a Gold Essence they need one Gold Essence Container, Goldweed, Quicksilver and Gold Dust. The skill level on the Goldweed and the Gold Dust determines the rarity as well as the skill level on the Gold Essence.
A list of the names of Gold Essences is found on the Talisman Making page.