This study develops a method for the synthesis of environmentally safe, non-toxic, and color-tunable fluorescent nanomaterials using AuCl3 and toluene without additional surfactants or reduction agents. A facile method for the fluorescence control of gold nanoclusters using simple ultrasonic irradiation is reported. The cluster composition, size, and emission wavelength can be controlled by the ultrasonic irradiation time. There is low photobleaching and the quantum yields are sufficient for optical devices and biosensors. The proper control of ultrasonic conditions such as exposure time, temperature, frequency, duty cycle, and intensity allows the composition and color of fluorescent gold nanoclusters to be adjusted. The obtained materials will be very useful for multicolor molecular probe design in the future.