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First: is it a scar or a mark?
Stand at a mirror in soft, even light and look straight on. Then turn so light rakes across your cheek from the side.
If discolouration is visible straight on but the surface looks smooth in side light, you are dealing with post-inflammatory marks — red or purple in lighter skin, brown in deeper skin. These are not scars. They fade, though slowly, and they respond to pigment-focused care and disciplined sun protection.
If side light casts small shadows, the structure of the skin has changed. That is a true scar, and no serum will lift it.
This one distinction determines everything that follows — including whether you should be spending money on brightening products at all.