A tertiary color is made by mixing a primary color with the secondary color next to it on the color wheel, in roughly equal amounts. There are six of them on the standard twelve-part wheel, and they sit in the gaps between the three primaries and the three secondaries.
Red, yellow and blue are the primaries. Orange, green and violet — each a mix of two primaries — are the secondaries. The tertiaries are what you get one step further in.
The Six Tertiary Colors
Each one carries a two-part name, primary first, secondary second:
- Red-orange — red mixed with orange (vermilion sits here)
- Yellow-orange — yellow mixed with orange (amber)
- Yellow-green — yellow mixed with green (chartreuse)
- Blue-green — blue mixed with green (teal, turquoise)
- Blue-violet — blue mixed with violet (indigo)
- Red-violet — red mixed with violet (magenta, plum)
Lay them on the wheel and every tertiary sits exactly between the two colors it was mixed from. Its complement — the color directly opposite — is always another tertiary: blue-green faces red-orange, yellow-green faces red-violet.
How They're Mixed
Start with the secondary. Mix equal parts of two primaries — red and yellow — and you have orange. Now add more red than the orange already contains, and the mix slides toward red-orange. Add more yellow instead and it slides toward yellow-orange.
With paint, the proportions are never quite equal in practice. Pigments differ in strength: a little blue overpowers a lot of yellow, so "equal parts" on the wheel means "until it looks halfway" on the palette. That's also why a painter's wheel is a guide to relationships rather than a recipe.
One Name, Two Definitions
There is a second, older meaning. Merriam-Webster's entry gives both: a tertiary color is either a primary mixed with an adjacent secondary, or two secondaries mixed together — orange with green, green with violet, violet with orange. Mixing two secondaries gives muted, earthy colors — olive, russet, slate — because each secondary already contains two primaries, so the mix contains all three, and all three together pull toward gray or brown.
Design courses and most color-wheel diagrams use the first definition and sometimes call those six colors "intermediate" instead. Painters often use the second, because the muted secondary-plus-secondary mixes are where most natural colors live. If a source seems to contradict another on what "tertiary" means, this is why.
Why Painters Care More Than Designers Do
Look at anything real — a brick wall, a dog, a hillside in October, a face — and almost none of it is a primary or a secondary. It's red-orange leaning brown, yellow-green dulled with its complement, blue-violet in a shadow. The pure colors on the wheel are reference points; the tertiaries and their grayed-down versions are the paint.
That's the practical reason to know the six names. When a mix looks wrong, the fix is usually a step along the wheel — the green needs to lean yellow, the shadow needs a touch of its complement — and the tertiary names tell you which direction to step.
Where Tertiaries Hide in a Numbered Kit
A paint by numbers kit arrives with every color already mixed, so you never mix a tertiary yourself. But they're there, and they're the difference between the two versions of a design.
A 24-color version carries the primaries, the secondaries, the neutrals and a first set of in-between tones — enough for clean, graphic shapes. The 36-color version adds more of the tertiaries and their shades: the extra oranges in a sunset sky, the three greens in one hedge, the blue-violets in a shadow on snow. That's why 36 colors reads as softer and more gradual, and why 24 colors reads as bolder; the guide to choosing 24 or 36 colors for a first kit goes through it design by design, and the guide to what makes a kit difficult explains why closely matched tones ask for more attention at the edges.
A custom kit printed with 48 colors takes it one step further, with enough in-between tones to hold the gradients of a photograph — the point where a numbered canvas and a mixed palette start to look alike.
Six names, one wheel, and most of the world's color in the gaps between the ones everybody knows.
