C-Firma™ Vitamin C Day Serum

Shares ferulic acid and tocopherol for the antioxidant boost, but swaps ascorbic acid for gentler derivatives (3-o-ethyl ascorbic acid, tetrahexyldecyl ascorbate) which are much weaker and won't brighten as aggressively.

Uses magnesium ascorbyl phosphate (a mild, stable vitamin C derivative) instead of ascorbic acid, and while tocopherol is shared, this is an eye serum with fragrance oils rather than a true C-Firma match.

It has plain ascorbic acid but no ferulic acid, no vitamin E, and no antioxidant complex (grape, licorice, pumpkin ferment) that make C-Firma work; it's also an eye serum at unknown/likely low vitamin C concentration.

Relies on ascorbyl glucoside, a much gentler vitamin C derivative, not the potent ascorbic acid used in C-Firma, and lacks ferulic acid/tocopherol antioxidant support entirely.

This is an anti-aging day cream with niacinamide and a UV filter, not a vitamin C serum; it lacks ascorbic acid altogether despite the deterministic overlap claim.