Everything I researched about Vitamin C serum say the color should be clear and if it has turned brownish then it has oxidized. I don't know if this serum is caramel-colored because it has other ingredients (CBD, etc) or if it was already old when shipped to me. I attached a photo of the serum against a white counter. Either way, I will use it up but order a different brand of Vitamin C serum next time and keep it refrigerated to prevent oxidation. This product does goes on very nicely, but at $80 for a bottle, I want something that is not already oxidized.