What is GHK Cu Collagen and Elastin Support Neurogan Health 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 N2 (N Glycyl L histidyl) L lysinato(2 )]copper 89030 95 5 wiki Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine