An article includes a first layer comprising a substrate having one or more images applied thereto. A second layer applied on each image and comprising one or more first and second portions, the first portion and second portions each in communication with a first image area and a second image area of an image, respectively. The second layer comprises a coating composition comprising fully exfoliated single sheets of graphene. The first and second portions comprise first and second detectable properties, respectively, having a value correlated with the graphene. The first and/or second detectable properties each comprise a first X-ray diffraction pattern, a first electrical conductivity, and one or more of a thermal conductivity, an optical property. The first and second detectable properties together create a distinctive signature for the article.