High-strength niacinamide for a brighter, more even-looking tone.
A 15% niacinamide serum with ascorbyl glucoside, multiple forms of hyaluronic acid and micro-fine diamond powder. It helps improve the look of dullness and uneven tone while leaving an immediate luminous finish.
Secure checkout on Shopify, powered by Vegalab — Youlief’s distributor in the United States.
These photos document individual customer experiences. Youlief has not independently verified lighting, camera settings, timing, retouching status, or that product use alone caused the visible differences. They are not a promise of typical or guaranteed results.
Before
AfterSkin tone looked brighter and more even.
“My skin looked softer and more even-toned than I expected. The watery texture also absorbed quickly into my dry skin.”
High-strength niacinamide for a brighter, more even-looking tone.
A stable vitamin C derivative widely used in appearance-focused brightening formulas.
Reflects light across the skin for an immediate luminous finish.
Keeps a high-strength serum feeling hydrated and comfortable.
A primary skin-irritation test was completed on sensitive-skin subjects at an independent testing centre.
These photos document individual customer experiences. Youlief has not independently verified lighting, camera settings, timing, retouching status, or that product use alone caused the visible differences. They are not a promise of typical or guaranteed results.
Before
AfterThe look of uneven tone appeared softened.
“With consistent use, I could see a difference in the look of my skin tone. My skin appeared clearer and naturally radiant.”
Before
AfterSkin looked clearer and more luminous.
“After using two DIA serums for two weeks, my skin looked clean and bright. The watery texture spread easily across my face.”
Customer photos from Korea. Review excerpts translated from Korean and adapted only for length and cosmetic-claim wording.
Apply 2–3 drops after toner morning or evening. If you are new to high-strength niacinamide, begin every other day. Follow with moisturizer and use sunscreen every morning.
Water, Niacinamide, Butylene Glycol, Glycerin, 1,2-Hexanediol, Ascorbyl Glucoside, Arginine, Propanediol, Xanthan Gum, Carbomer, Betaine, Ethylhexylglycerin, Allantoin, Adenosine, Hydrolyzed Extensin, Disodium EDTA, Melia Azadirachta Flower Extract, Ocimum Sanctum Leaf Extract, Pentylene Glycol, Melia Azadirachta Leaf Extract, Panthenol, Curcuma Longa (Turmeric) Root Extract, Corallina Officinalis Extract, Paeonia Suffruticosa Root Extract, Sodium Hyaluronate, Polymethylsilsesquioxane, Hyaluronic Acid, Hydrolyzed Hyaluronic Acid, Hydrolyzed Sodium Hyaluronate, Hydroxypropyltrimonium Hyaluronate, Potassium Hyaluronate, Sodium Hyaluronate Crosspolymer, Sodium Acetylated Hyaluronate, Diamond Powder
Size: 30 mL / 1.01 fl. oz.
SKU: YLF-DIA-TON
Made in South Korea.
Distributed in the United States by Vegalab LLC.
For external use only. Avoid direct contact with the eyes; rinse with water if contact occurs. Discontinue use if redness, itching or discomfort develops and consult a physician if it persists. Do not apply to broken or irritated skin. Store away from direct sunlight and keep out of reach of children.
Ships across the United States via USPS — $10 flat, free on orders of $100 or more. Unopened, unused products may be returned within 14 days of delivery for a refund of the product price — email us for a return authorization first. Opened or used products cannot be returned for hygiene reasons. See our Shipping & Returns page for full details.
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