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 Interplay of the CuCu distance and coordination geometry as a factor affecting the quantum efficiency in dimeric copper(i) halide complexes with derivatives of 4 pyrazolylpyrimidine 2 thiol Dalton Transactions (RSC Publishing) Buy GHK Cu Peptide 99%+ Purity GHK Cu for Research Ghk Cu Copper Peptide: Uncover Its Full Potential