Product Overview
A high-strength vitamin C serum formulated with 23% pure ascorbic acid for practitioners wanting intensive care for visible dark spots, post-blemish marks, dullness and uneven-looking skin tone.
Unlike gentler vitamin C derivative formulas, this serum uses a high concentration of pure vitamin C, supported by tocotrienols and tocopherol (vitamin E), glutathione, niacinamide, 3-O-ethyl ascorbic acid, panthenol, sodium hyaluronate, squalane and allantoin.
Within the Glass Ritual Pigmentation Collection, this sits firmly in the advanced targeted-treatment category rather than being an introductory brightening serum.
Why We Chose It
We chose the COSRX Advanced The Vitamin C 23 Serum because the Pigmentation Collection should provide different treatment strengths rather than pretending every practitioner needs the same formula.
At 23% pure ascorbic acid, this is one of the more intensive vitamin C options in the collection.
The formula doesn't rely on vitamin C alone. It combines pure ascorbic acid with 3-O-ethyl ascorbic acid, tocotrienols, tocopherol, glutathione and niacinamide, creating a broader antioxidant and tone-supporting system.
Panthenol, sodium hyaluronate, squalane and allantoin provide additional hydration and skin-conditioning support.
We position this serum for practitioners who are already comfortable with active skincare and intentionally want a high-strength vitamin C treatment, rather than automatically recommending it to everyone concerned about pigmentation.
Benefits
- Contains 23% pure vitamin C
- Helps improve the appearance of dark spots
- Supports a brighter, more even-looking complexion
- Helps address post-blemish marks
- Provides strong antioxidant support
- Helps improve the appearance of dullness
- Contains both pure ascorbic acid and a vitamin C derivative
- Tocotrienols and tocopherol provide additional antioxidant support
- Glutathione complements the antioxidant system
- Niacinamide provides additional tone and barrier support
- Sodium hyaluronate supports hydration
- Panthenol and allantoin provide skin-conditioning support
- Squalane provides lightweight emollient care
Who It's For
Consider this serum if you are concerned about:
- Persistent-looking dark spots
- Post-blemish marks
- Uneven-looking skin tone
- Dullness
- Loss of radiance
- Wanting a high-strength vitamin C treatment
- Already having experience using active skincare
- Wanting a more intensive option than a vitamin C derivative serum
This would not be our automatic starting recommendation for highly sensitive skin or someone completely new to vitamin C.
How to Use
After cleansing and toning, apply approximately 2–3 drops over the face.
Gently pat until absorbed.
Follow with moisturiser.
When used during the daytime, follow with appropriate sun protection.
Because this is a high-concentration vitamin C treatment, introduce it gradually and observe how your skin responds before increasing frequency.
Ritual Position
Cleanse → Tone → COSRX Vitamin C 23 Serum → Moisturise
This occupies the advanced targeted-treatment stage of the Glass Ritual.
Glass Ritual Pairing
This serum does not need to be layered with every other pigmentation treatment in the collection.
A deliberate routine may simply be:
Gentle Cleanser → Hydrating Toner → COSRX Vitamin C 23 Serum → Barrier-Supportive Moisturiser
Avoid assuming that combining 23% vitamin C + exfoliating acids + retinol + multiple pigmentation serums in one routine will produce better results.
If using other intensive actives, separate them according to skin tolerance and the instructions for those products.
Within the collection, there is an important distinction:
GOODAL Green Tangerine Vita C Dark Spot Care Serum
A more approachable option built around green tangerine and a vitamin C derivative.
COSRX Advanced The Vitamin C 23 Serum
A substantially stronger option containing 23% pure ascorbic acid, better suited to experienced vitamin C users intentionally seeking higher-strength treatment.
Glass Ritual Principle: Stronger is a treatment option—not automatically a better starting point.
Key Ingredients
Pure Ascorbic Acid — 23%
A potent form of vitamin C providing antioxidant support and helping improve the appearance of pigmentation, dullness and uneven-looking tone.
3-O-Ethyl Ascorbic Acid
A vitamin C derivative that complements the formula's primary pure ascorbic acid.
Tocotrienols + Tocopherol
Forms of vitamin E that provide additional antioxidant support.
Glutathione
An antioxidant that complements the serum's broader antioxidant system.
Niacinamide
Supports a brighter, more even-looking complexion and healthy barrier function.
Sodium Hyaluronate
Helps attract and retain moisture.
Panthenol
Provides hydration and skin-conditioning support.
Squalane
Provides lightweight emollient support.
Allantoin
Provides soothing and skin-conditioning support.
Adenosine
Provides skin-conditioning support and complements the formula's care for the appearance of early signs of ageing.
Full Ingredients
Aqua/Water, Ascorbic Acid (23%), Butylene Glycol, Dimethicone, Panthenol, 3-O-Ethyl Ascorbic Acid, Squalane, Sodium Hydroxide, Caffeine, Sodium Hyaluronate, Sodium Metaphosphate, Adenosine, Acetyl Glucosamine, Gardenia Florida Fruit Extract, Allantoin, Dextrin, Tocotrienols, Tocopherol, Elaeis Guineensis (Palm) Oil, Arginine, Niacinamide, Pentylene Glycol, Glutathione, Helianthus Annuus (Sunflower) Seed Oil, Methyl Trimethicone, Carthamus Tinctorius (Safflower) Seed Oil, Camellia Japonica Seed Oil, Daucus Carota Sativa (Carrot) Root Extract, Glycyrrhiza Glabra (Licorice) Root Extract, Beta-Carotene.
Safety & Ingredient Information
For external use only. Avoid direct contact with the eyes. Discontinue use if persistent irritation occurs.
This is a high-concentration 23% pure vitamin C formula. Introduce gradually, particularly if your skin is not accustomed to strong vitamin C treatments.
Avoid automatically combining it in the same routine with retinoids, strong exfoliating acids or other high-concentration active treatments. COSRX also advises separating this serum from copper-peptide products.
Pure vitamin C is inherently sensitive to oxidation. Close the product securely after use and follow the storage instructions provided with the product. COSRX currently advises using the serum within two months after opening.
Ingredient formulations can change over time. Always check the ingredient list printed on the specific product packaging you receive if you have known allergies or sensitivities.
Glass Ritual positions COSRX Advanced The Vitamin C 23 Serum as an advanced cosmetic treatment designed to help improve the appearance of dark spots, post-blemish marks, dullness and uneven-looking skin tone. It is not positioned as a treatment for a medical pigmentation disorder.
