A cosmetic instrument for applying a product to a surface includes a handle and an applicator. At least a portion of the cosmetic instrument may change from a first color to a second color in response to occurrence of a condition, such as exposure to electromagnetic radiation (e.g., ultraviolet light or infrared light) or when a temperature of the cosmetic instrument is within a predetermined temperature range. For example, one or more portions of the handle and/or applicator of the cosmetic instrument may be configured to change color in response to the occurrence of the condition.