Dark circles aren't on your skin. They're under it.
The skin there is 0.5mm thick — the thinnest on your body.
When the structure underneath collapses, the capillaries get exposed. Blood pools. Blue and purple bleed through to the surface.
Eye creams are glorified moisturisers. Moisture can't rebuild a collapsed structure. It can't thicken skin that's already translucent.
Retinol, caffeine, vitamin K — they all sit on the top the collapsed structure.
Six weeks in. Half the jar gone. Same darkness.
Concealer layers pigment on top. By midday it oxidises to orange-grey and the darkness shows through again.
The sheer tint is different. It sits on the surface the microfilm has already flattened.
It adapts to your skin tone on contact. No shade-matching between "ivory" and "porcelain."
It neutralises the colour pushing through.
Flat surface. Matched colour. Nothing showing through.