Copper Peptide (GHK Cu) Supplier Cosmetic Ingredient for Formulators Creative Peptides 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 Copper Tripeptide (GHK Cu) for Advanced Skincare & Haircare Formulatio GHK Cu 50 mg Copper Peptide Research Grade PRG