A GHK Cu face serum appears blue because the active ingredient, GHK Cu (copper peptide), is naturally a blue colored powder, meaning its inherent color transfers to the serum when mixed in; this blue hue GHK Cu Peptide Skin Cream Levers.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 Skincare Copper Peptide GHk Cu & Methylene Blue Global Ubuy Copper Peptide Serum for Dull & Mature Skin VALNCIA Glutathione Injections: Side Effects & Benefits