A method of producing a custom color particulate toner for use in a two-component developer by mixing two or more component color toners. The component color toners are each surface treated with a blend of two or more types of silica particles, which differ in the functional groups appended to them. The silica blend for each component color toner is chosen so that, when the component color toners are mixed together to form the custom color mixture, they will all tribocharge to the same charge-to-mass ratio when mixed with a carrier to form a developer.