Egyptian Blue (EB, CaCuSi₄O₁₀) and Han Blue (HB, BaCuSi₄O₁₀) are ancient blue pigments renowned for their ability to efficiently convert red light into infrared emission. In this work, their application in luminescent formulations capable of generating distinct optical signals depending on the excitation wavelength is presented. The study focuses on the development of multicomponent luminescent composites that emit in the red and near-infrared (NIR) spectral regions as a function of the excitation source, while integrating at least three levels of security [1]. Such luminescent systems represent promising tools for anti-counterfeiting strategies and authenticity verification in the field of cultural heritage [2]. By combining luminescent materials with different chemical compositions and physical properties, synergistic effects are obtained.

Furthermore, the potential use of these pigments as markers for assessing the consolidation of lime-based materials and mortars is explored [3]. The formulation process involved systematic investigations into the low-cost synthesis of blue pigments using microwave irradiation, as well as the production of stable colloidal systems. Key parameters such as pigment concentration, pH, and the presence of additives influencing stability, transparency, and optical performance were examined. The nature of the interactions governing formulation stability was also analyzed.