A method of identifying an article comprising the steps of: a) providing an article comprising fluorescent marker particles, wherein - the fluorescent marker particles are distributed in the entire volume of the article or in a portion of the volume of the article and the fluorescent marker particles are present in this entire volume or in said portion of the volume in a random distribution; - the volume in which the fluorescent marker particles are distributed comprises a sub-volume; - the sub-volume contains at least a portion of the fluorescent marker particles; - the sub-volume is at least partially transmissive to electromagnetic radiation having a wavelength in the visible range and/or in the near infrared range and/or in the UVA range; and - a portion of the surface of the sub-volume is identical to a portion of the surface of the article; b) positioning a detection device by means of optical properties of the article and/or by means of mechanical elements of the article and/or by means of positioning aids so that the fluorescent marker particles can be detected in the sub-volume by means of the detection device; c) determining the random spatial distribution of the fluorescent marker particles in the sub-volume by means of the detection device; and d) matching the determined random spatial distribution with stored information about the random spatial arrangement for identifying the article. a) providing an article comprising fluorescent marker particles, wherein - the fluorescent marker particles are distributed in the entire volume of the article or in a portion of the volume of the article and the fluorescent marker particles are present in this entire volume or in said portion of the volume in a random distribution; - the volume in which the fluorescent marker particles are distributed comprises a sub-volume; - the sub-volume contains at least a portion of the fluorescent marker particles; - the sub-volume is at least partially transmissive to electromagnetic radiation having a wavelength in the visible range and/or in the near infrared range and/or in the UVA range; and - a portion of the surface of the sub-volume is identical to a portion of the surface of the article; - the fluorescent marker particles are distributed in the entire volume of the article or in a portion of the volume of the article and the fluorescent marker particles are present in this entire volume or in said portion of the volume in a random distribution; - the volume in which the fluorescent marker particles are distributed comprises a sub-volume; - the sub-volume contains at least a portion of the fluorescent marker particles; - the sub-volume is at least partially transmissive to electromagnetic radiation having a wavelength in the visible range and/or in the near infrared range and/or in the UVA range; and - a portion of the surface of the sub-volume is identical to a portion of the surface of the article; b) positioning a detection device by means of optical properties of the article and/or by means of mechanical elements of the article and/or by means of positioning aids so that the fluorescent marker particles can be detected in the sub-volume by means of the detection device; c) determining the random spatial distribution of the fluorescent marker particles in the sub-volume by means of the detection device; and d) matching the determined random spatial distribution with stored information about the random spatial arrangement for identifying the article.