KPV GHK Cu (10 50 MG) Sigma Compounds The Best Peptides For Glowing Skin: From GHK Cu To TB 500 One of my patients has shared this picture with me as she felt it was odd that this peptide had this very vivid blue colour, while her other peptides had a clear 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