Koreana Skin GHK Cu Copper Peptide Mask Revitalizing & Firming Hydrogel Sheet Mask GHK CU 50mg Vial Copper Peptide Pure Bio Labs 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: What It Does for Body Composition and Metabolic Health GHK Cu (Raw) 1g Ion Peptide