Your copper peptide product should be this exact blue. If it isn't, you already have your answer. GHK Cu is blue because of coordination chemistry, not dye. The Cu ion at the center 99% Pure Copper Peptides (ghk cu) Great for DIY 1 Gram Etsy GHK Cu Peptide (50mg) Advanced Skin Rejuvenation & Healing Support 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 The GHK Cu delays aging in Caenorhabditis elegans via coordinated regulation of mitochondrial function and activation of DAF 16 SKN 1 pathways Biogerontology Springer Nature Link