Quick answer
Why is GHK-Cu blue?
Because of the copper. GHK-Cu is a copper-bound peptide, and the copper(II) ion gives the reconstituted solution its blue tint.
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It's normal — and a good sign
The blue colour is a marker of authentic GHK-Cu, not a defect or contamination. If anything, a completely colourless "GHK-Cu" solution is the red flag, since the copper that defines the compound should tint it blue.
Learn more
See the GHK-Cu deep-dive for how the copper peptide works.
Frequently asked questions
Is a darker blue stronger?
Not reliably — colour intensity varies with concentration and is not a precise potency measure. The Certificate of Analysis is the real check.