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 Amazon.com: Skin Perfection Copper Peptide Serum GHK CU 1% for Face & Hair Copper Peptides for Skin, Hair, & Scalp 1% Blue Liquid for Face, Neck, Body, Scalp Multi Use Serum Booster with Copper Peptides Ingredient Guide Nubeean Noosa GHK Cu: The Midlife Peptide Your Skin Has Been Missing (and Why It's Not Just About Wrinkles) Relished Food Holistic Nutrition