The Pretty Purple Peptide with Powerful Benefits That gorgeous blue purple solution isn't just for looksit's GHK Cu, one of the most studied peptides in regenerative medicine. Here's what it can do for GHK Cu (100MG) LYOPHILIZED TENNESSEE PEPTIDES GHK Cu Slimfit Compounds 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