Your copper peptide product should be this exact blue. If it isn't, you already have your answer. GHK Cu is blue because of coordination chemistry, not dye. The Cu ion at the center GHK Cu Peptide Foundry Premium Research Peptides Coordination geometry of the copper(II) peptide core obtained by QM MM Download Scientific Diagram Theoretical study of copper binding to GHK peptide ScienceDirect GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link Figure 6 from GHK Copper Peptide in Skin Remodeling and Anti Aging ! GHK Cu in Skin Remodeling Semantic Scholar