Abstract: A security feature (1) that is used with a substrate (2). The security feature includes a plurality of fluorescent micro-particles (1A) that form a background component of the security feature and a plurality of fluorescent discrete particles (1B) that form a foreground component of the security feature. The discrete particles are larger in size than the micro-particles and are optically distinguishable from the micro-particles under at least one illumination condition. In the preferred embodiment the security feature is applied as a coating to the substrate, and the security feature further includes a coating binder (1C) in which the micro-particles and the discrete particles are contained. The coating binder can be made of, for example, at least one of an ink base, an adhesive, an epoxy, a varnish, a polymer solution, or a dry material having binding properties. The coating binder may be substantially transparent or substantially opaque.