COSRX the vitamin C 23 The Vitamin C23 Serum Although there are stains on the outer text, there are no abnormalities inside, so the product condition is set to "no noticeable stains." I bought this as a measure against UV rays in the summer, but I'm changing to something different because I'm concerned about dryness in the fall and winter, so I'm putting it up for sale. It has a unique smell.