Copper Peptide (GHK Cu) Supplier Cosmetic Ingredient for Formulators Creative Peptides GHK Cu: The Elegant Copper Peptide for Skin and Scalp Renewal Renew Vitality Copper Peptide GHK Cu for Sale Stanford Advanced Materials 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 Theoretical study of copper binding to GHK peptide ScienceDirect