Color, Depth and Undertone
Depth is one axis and undertone is another, and most shade guides only know the first. Shade matching, why the standard undertone tests fail, and what to do when the foundation you own looks ashy, orange or gray.
Two axes, not one. Depth runs light to deep and undertone runs green to red, and confusing the two is why a foundation can be the right darkness and still look wrong. How skin tone is actually measured covers the difference between the scales, including the one most beauty writing borrows for the wrong purpose.
Olive gets treated as a real category here rather than a footnote, because it sits on the green side of an axis most shade ranges decline to acknowledge, which is precisely why the usual vein and jewelry tests fail on it.
The first guides under this heading are being written.
Browse everything published so far →