You bought the perfect foundation last October. It looked right. You wore it through winter and felt confident. Then summer came. You got a little sun. You held the bottle up to your face and it was suddenly wrong —too light, off-colour, nothing like October.
So you bought a new one. This one looked right in May. Wrong by August.
This is not your skin being difficult. This is overtone and undertone doing completely different things —and nobody told you they were separate.
Overtone is what changes. It is the visible surface colour of your skin right now. Sun exposure deepens it. Winter fades it. A month in a cold city lightens it. A week at a beach darkens it. Your overtone is always moving.
Undertone is what stays. It is the fixed, biological colour beneath the surface. It is warm, cool, neutral, or olive —and it does not move. It was the same the day you were born. It will be the same next decade.
When you buy a new foundation every season, you are re-matching your overtone. This is correct —the depth number should reflect your current skin tone. But the suffix —the W, C, N, or G after the number —should never change. That is your undertone. That is fixed.
The right approach: change the shade number with the seasons. Never change the undertone letter.
Dear Brown Girl, your skin changes beautifully with every season. Your undertone is the one thing that never wavers.