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 50mg Vial Copper Peptide Pure Bio Labs GHK Cu Peptide: What It Does for Body Composition and Metabolic Health Buy GHK Cu 100mg (Copper Peptide) 99% Purity, USA Made Peptide Therapy in Jupiter, FL Aven Clinic GHK Cu (Raw) 1g Ion Peptide