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 SKINHI BLUE01 Copper Peptide GHK CU 1.4% All Over Body Care Size 50ml Aytz Chayim Aromatherapy 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 Close Blue Copper Peptides Ghk cu Powder Stock Photo 2682985977 Shutterstock