Provided are gold-coated flat silver particles, a dispersion including the gold-coated flat silver particles and a dispersion medium, a method of the dispersion, a coating film including the gold-coated flat silver particles, and an antireflection optical member. The gold-coated flat silver particles include flat silver particles and a gold coating layer, in which an average thickness of the gold coating layer on principal planes of the particles is 0.1 nm to 2 nm, and a ratio of the average thickness of the gold coating layer on the principal planes of the particles to an average thickness of the gold coating layer on edge surfaces of the particles is 0.02 or higher.