GHK Cu: The Peptide That Supports Healthy Aging GHK Cu (copper peptide) is naturally occurring in the body and plays a role in supporting skin health, collagen production, and tissue repair. As 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 Copper Peptide Research Grade PeptiSense EU PeptiSense GHK CU 1 gram FITSKNS Peptides GHK Cu Peptide Therapy: The Definitive Clinical Guide to Gene Modulation, Protocols, and Efficacy