99% Pure Copper Peptides (ghk cu) Great for DIY 1 Gram Etsy 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 (50mg) Advanced Skin Rejuvenation & Healing Support 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 AHUALYN